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Time-dependent inhibition of diamine oxidase by carbonyl-group reagents and urea.

1. The behaviour of several carbonyl group reagents and urea as time-dependent inhibitors of both pig kidney and human placental diamine oxidase is described. 2. Plots of log (vt/vo) against time were not linear with these reagents as the usual theories predict. 3. This was particularly the case with aminoguanidine and phenylhydrazine and a thorough study of the effects of these compounds on the human placental diamine oxidase is described. 4. By applying a new theory for time-dependent inhibition, the inhibition of diamine oxidase by aminoguanidine and phenylhydrazine is adequately accounted for. 5. The time-dependent recovery of activity on addition of sodium pyruvate suggested that the compounds used are acting solely as carbonyl group reagents, inhibiting by Schiff-base formation at the active-site carbonyl group.

Amine Oxidase (Copper-Containing)

Oxidative deamination of biogenic amines by intestinal amine oxidases: histamine is specifically inactivated by diamine oxidase.

The ability of the gut to inactivate various amines by oxidative deamination was tested with a 130-fold purified amine oxidase preparation from dog small intestine. Of 34 amines tested, putrescine, benzylamine, cadaverine, and serotonin were the most favourable substrates. Histamine was inactivated rapidly by this enzyme preparation, too. Histamine derivatives methylated at the imidazole nucleus were also deaminated, whereas Nalpha-methylhistamine was only a poor substrate and Nalpha, Nalpha-dimethylhistamine was not a substrate at all. Using a second procedure for the purification of amine oxidases from gut, the separation of a soluble monoamine oxidase from diamine oxidase was achieved by gel filtration on Sephadex G-200. The diamine oxidase deaminated putrescine (Km = 1.3 x 10(-4)M) and histamine (Km = 6.6 x 10(-5)M), but not serotonin, and was inhibited by aminoguanidine, but not by pargyline. The soluble monoamine oxidase inactivated serotonin (Km = 4.5 x 10(-4)M), but not histamine and putrescine and was inhibited by pargyline, but not by aminoguanidine. It was concluded that in dog small intestine (as well as in rabbit small intestine) only diamine oxidase was capable of inactivating histamine by oxidative deamination.

Amine Oxidase (Copper-Containing)

Postheparin-diamine oxidase (histaminase) in anaphylaxis.

The level of plasma postheparin-diamine oxidase was determined in two patients three days after an anaphylactic shock and was controlled four weeks, and also six months later. A decrease of the enzyme levels to about 10% of a control group was found and a slow enzyme increase to about 40% observed six months later. It seems probable that in anaphylaxis a depletion of the enzyme in liver and small intestine occurs as could be shown in animals after heparin load.

Adolescent

Diamine oxidase activity and histamine release in dogs following acute mesenteric artery occlusion.

Following superior mesenteric artery occlusion and revascularization in dogs all animals died in a circulatory collapse state. However, pretreatment by aminoguanidine, the strong and specific inhibitor of diamine oxidase, accelerated the circulatory break-down significantly and increased the venous plasma histamine concentrattions up to levels which also in normal dogs are effective in the circulatory system. Furthermore, the haematocrit increased significantly more in the aminoguanidine-treated animals than in the dogs treated by saline. No changes in plasma diamine oxidase activity were observed in saline-treated animals during intestinal ischemia and following revascularization. In aminoguanidine-treated animals no enzymic activity could be measured. The results were interpreted by a protective role of intestinal diamine oxidase in intestinal ischemia. Enhancement of the enzymic activity in patients, for instance by heparin, may be helpful in mesenteric infarction disease.

Amine Oxidase (Copper-Containing)

Blocking of olive oil induced plasma protein escape from the intestinal circulation by histamine antagonists and by a diamine oxidase releasing agent.

Earlier studies have shown that feeding of olive oil to rats substantially increased the plasma protein in the intestinal lymph. The possibility of histamine mediating this response was examined. The plasma protein escape from intestinal circulation after olive oil feeding was measured in rats in terms of the amount of Evans Blue labelled plasma protein found in the intestinal lymph. Animals treated with histamine antagonists (H1-receptor antagonist pyrilamine, 16-22 mg/kg i.p., plus H2-receptor antagonist Burimamide, 12-16 mg/kg i.p.) did not show an increase in the quantity of lymphatic plasma protein. Heparin pretreatment which releases the histaminolytic enzyme, diamine oxidase, into the interstitial space also prevented the increased accumulation of labelled plasma protein in the lymph after olive oil ingestion. Based on these observations, histamine appears to act on the intestinal microcirculation during olive oil absorption and allows larger quantities of plasma proteins to leave the intestinal circulation.

Amine Oxidase (Copper-Containing)

Delayed cold-induced urticaria: a dominantly inherited disorder.

A delayed cutaneous response to cold, characterized by areas of erythematous, edematous deep swelling at 9 to 18 hr after experimental ice challenge, was recognized in a 10-yr-old boy and several members of his family. Biopsy of the cold-induced lesion showed edema and an infiltrate of mononuclear cells; mast cells were normal, and immunoglobulins, complement factors, and fibrin were not detected by immunofluorescence techniques. Local cold challenge did not release histamine or induce alterations in the complement system or the enzymes, histaminase, and histamine methyl transferase. The delayed cutaneous response to cold could not be passively transferred with serum or tissue extracts to monkey skin. Family studies suggested an autosomal-dominant mode of inheritance.

Amine Oxidase (Copper-Containing)

Association of diamine oxidase and ornithine decarboxylase with maturing cells in rapidly proliferating epithelium.

Diamine oxidase and ornithine decarboxylase activities are shown to have a parallel distribution across rat small intestine mucosa; levels of both enzyme activities are sharply higher in mature cells in the villus tip region than in proliferating cells in the crypt areas. Histidine decarboxylase levels were not measurable in the same cell preparations and aromatic-L-amino-acid decarboxylase activity was distributed in an opposite pattern to diamine oxidase and ornithine decarboxylase. The results suggest that intestinal diamine oxidase could be involved with polyamine metabolism. The new findings for ornithine decarboxylase suggest an in vivo role for polyamines in non-proliferative cells; rat small intestinal mucosa may be an excellent model for investigating the function of polyamines in regenerating cells.

Amine Oxidase (Copper-Containing)

Variable content of histaminase, L-dopa decarboxylase and calcitonin in small-cell carcinoma of the lung. Biologic and clinical implications.

To ascertain whether the content of endocrine markers is constant in small-cell carcinoma of the lung, levels of three markers of medullary thyroid carcinoma were studied in this tumor. Histaminase was increased in six of six primary tumors (three to 14,000 times), L-dopa decarboxylase in four of six (six to 30 times), and calcitonin in one of one (eight times) over levels in adjacent lung. Marker levels in mediastinal metastases reflected those in primary tumors in four of five patients. However, in four of seven, multiple hepatic metastases contained low to absent levels despite simultaneously high values in chest lesions. Immunohistochemical studies of histaminase revealed that within each primary tumor different cells contained different amounts of the enzyme. Since marker content varied between tumor cells, between primary tumors and between metastases in individual patients we conclude that circulating levels of these three markers cannot be expected necessarily to mirror tumor burden in patients with small-cell lung tumors.

APUD Cells

Purification and properties of human amniotic fluid diamine oxidase.

Diamine oxidase (DAO) was purified from amniotic fluid. The activity was separated in two DAO fractions with pI values of 5.8 and 4.0. Molecular weight were found to be 245,000 and 485,000, respectively, with subunit molecular weight of 110,000. This indicated that they probably are dimer and tetramer of the same DAO subunit. The enzyme was active against putrescine and histamine and was strongly inhibited by carbonyl group reagents. A Ping Pong Bi Ter enzyme reaction mechanism is probable. The diamine, with one amino group protonized, is suggested to be responsible for interaction with the enzyme.

Amine Oxidase (Copper-Containing)

The selective eosinophil chemotactic activity of histamine.

Histamine diphosphate was shown to selectively attract human eosinophils from mixed granulocyte populations when over 20% eosinophils were used in a modified Boyden chamber chemotactic assay system. This effect of histamine is abolished by incubation with diamine oxidase (histaminase) and was generated by decarboxylation of L-histidine. A linear dose dependent increase in eosinophil migration was observed between 3 X 10(-7) M and 1.25 X 10(-6) M, while higher concentrations of histamine inhibited the migration of eosinophils. The attractant activity of histamine was not inhibited by H-1 or H-2 receptor antagonists, however, the inhibition of migration observed at higher histamine concentrations was reversed by metiamine, an H-2 receptor antagonist. The effects of histamine upon eosinophil migration were demonstrable using three different assays: (a) counting cells that had traversed 5-mum pore, 12-mum thick polycarbonate filters, (b) counting cells that had migrated various distances into a 3-mum pore, 145-mum cellulose nitrate filters, or (c) measuring the number of cells that had traversed an upper polycarbonate filter and migrated into a lower cellulose nitrate filter using 15Cr-labeled cells. The ability of histamine to enhance eosinophil migration was shown to be dependent upon the presence of a concentration gradient; histamine did not cause a dose-dependent increase in random motility. Furthermore, preincubation of the eosinophils with histamine deactivate the cells to further stimulation by histamine or by C5a. It is concluded that in low doses histamine is a chemoattractant for human eosinophils, while in higher doses histamine inhibits eosinophil migration. These observations may relate to the influx and localization of eosinophils in immediate hypersensitivity reactions.

Amine Oxidase (Copper-Containing)