F. Buffoni

Semicarbazide-sensitive amine oxidase activity (SSAO) of rat epididymal white adipose tissue

An amine oxidase activity distinguishable from MAO, which is inhibited by carbonyl reagents is present in rat epididymal WAT. This enzyme, referred to as semicarbazide-sensitive amine oxidase (SSAO), appears concentrated in adipose cells. Close homologies between WAT SSAO and the circulating plasma BAO are discussed.

Skin Wound Healing: Some Biochemical Parameters in Guinea‐pig

Abstract— Hairs were removed from the dorsal skin of guinea‐pigs and 5–6 wounds (7 × 7 mm) were surgically induced by totally removing the epidermal and part of the dermal surface. They were then allowed to heal. The newly formed wound tissues were dissected at different times during the process and analysed by biochemical and histological methods. Hydroxyproline, proteins, DNA and semicarbazide‐sensitive amine oxidase (SSAO) were measured, as were [14C]leucine and [3H]thymidine incorporation in some samples. The peroxidase‐like activity of plasma albumin and the histology of wounds stained with haematoxylin‐eosin were also studied. It was shown that SSAO enzymes, which are present in normal guinea‐pig skin and have a high affinity for benzylamine are localized in fibroblasts. During skin healing in the newly formed tissue there was an increase in protein content which reached a maximum after 4–6 days; DNA content also increased. The rate of incorporation of [3H]thymidine and [14C]leucine paralleled DNA and protein content, respectively. The content of hydroxyproline had greatly decreased with respect to that in normal skin after 2–10 days. SSAO activity increased much less than DNA after 4 days whereas after 10–11 days it increased more than DNA, thus indicating that at this time it was probably produced by fibroblasts. No significant increase in the peroxidase‐like activity of albumin was observed 4, 8 or 11 days after surgery. Treatment of the animals with methylprednisolone acetate (20 mg kg−1, i.m.) two days before surgery decreased the rate of skin healing but did not alter the level of albumin peroxidase activity of the plasma. Histology showed that in the animals treated with this drug the re‐epithelialization was slower and after 11 days the wound appeared similar in appearance to the 8‐day control wounds. In the methylprednisolone‐treated animals a positive correlation was observed between the DNA content of regenerating tissue and the hydroxyproline content, whereas a negative correlation was observed in the control wounds. This correlation was in full agreement with the histological observation which showed an increased amount of cytogen collagen in the wounds of the treated animals. The simultaneous study of the biochemical parameters (DNA, proteins, SSAO, hydroxyproline) appears to be a good method for differentiating the pharmacological effects on the different cells which are responsible for wound healing.

Histamine lipolytic activity and semicarbazide-sensitive amine oxidase (SSAO) of rat white adipose tissue (WAT)

Histamine has previously been described as a possible substrate for the semicarbazide-sensitive amine oxidase activity (SSAO) of rat white adipose tissue (WAT). We report here on a histamine function in this tissue which concerns the activity of this deaminating system distinct from the classical diamine oxidase. Our results show that: (1) histamine plays a role in controlling rat adipose tissue lipolysis with the contribution of H1 and H2 receptors that participate in histamine lipolysis in an opposite way. Both H1 and H2 roles can be differentiated using selective agonists (2- and 4-methyl histamine) and antagonists (pyrilamine and cimetidine); (2) histamine might also control rat lipolysis induced by noradrenergic agonists; (3) the SSAO present in rat WAT controls histamine levels at the receptor sites as shown by the modification of histamine lipolytic potency obtained when inhibitors of this enzyme are used.

Further studies on semicarbazide-sensitive amine oxidase activities (SSAO) of white adipose tissue

1. White adipose tissue (WAT) from mice, rabbits, pigs and human subjects was investigated for the characterization of the tissue-bound semicarbazide-sensitive benzylamine oxidase activities (SSAO) present in each species. 2. Enzymes from mice, rabbits and pigs shared similar biochemical characteristics: they exerted histaminase activity, oxidized methylamine and acetylputrescine and were completely blocked by carbonyl reagents and by 3,5-ethoxy-4-aminomethylpyridyne (B24), in a dose-dependent fashion. 3. SSAO activity from human WAT had a lower affinity for benzylamine compared with enzymes in the other species and did not show any histaminase activity. 4. These results show that SSAO from human tissues might have different properties from SSAO of other species.

Immunofluorescence Histochemistry of Porcine Tissues Using Antibodies to Pig Plasma Amine Oxidase

The immunological reactivity of various tissues of the pig with rabbit antibodies raised to pig plasma amine oxidase have been studied. This paper presents evidence for the presence of a protein in the connective tissue of all the organs studied possessing the same immunological determinant as pig plasma amine oxidase.

Cultured preadipocytes produce a semicarbazide-sensitive amine oxidase (SSAO) activity*

The presence of an amine oxidase activity which is resistant to pargyline, an acetylenic MAO inhibitor, but sensitive to semicarbazide, is described in rat white and brown preadipocytes.

Rhein and derivatives. In vitro stúdies on their capacity to inhibit certain proteases

Abstract Rhein (R), 4,5-diacetylrhein (DAR), 4,5-dipropionylrhein (DPR) and 4,5-dibenzoyl-rhein (DBR) were studied in vitro against certain proteases (pepsin, trypsin, carboxypeptidase A, elastase) and compared to ɛ-aminocaproic acid and to aprotinin. Rhein and its derivatives inhibit the protease in the range of 10 −4 – 10 −5 M concentrations.

Histaminase activity in rat lung and its comparison with intestinal mucosal diamine oxidase

In rat lung microsomes, an enzyme showing high histaminase activity is present. The oxidation of histamine is dependent on the presence of two enzymic activities, both inhibited by alpha-aminoguanidine and by B24, an inhibitor of semicarbazide-sensitive amine oxidases (SSAO) which have benzylamine as preferential substrate. These enzymic activities differ in substrate specificity: one appears to be a classical tissue bound SSAO enzyme with high affinity for benzylamine, the other a diamine oxidase (DAO) with properties that are very different from the classical DAO. This latter enzyme is not inhibition by high histamine concentrations and is more active at pH 8.5 than at pH 7.4.

Biochemical pharmacology of amine oxidases

Abstract Monoamine oxidase, diamine oxidase, benzylamine oxidase and lysyl oxidase are the most important amine oxidases present in animal tissues. Some of their properties are discussed in this article.

Calcium modulatory properties of 2,6-dibutylbenzylamine (B25) in rat isolated vas deferens, cardiac and smooth muscle preparations

1 In rat isolated vas deferens the new compound 2,6‐dibutylbenzylamine (B25) evoked a series of repeating rhythmic contractions. Concentration‐response curves constructed for this effect were bell‐shaped, indicating a biphasic effect for this compound. By contrast, B25 depressed heart contractility without any visible positive inotropic or chronotropic activity. 2 Experiments with tetrodotoxin, reserpine, capsaicin, α‐adrenoceptor blocking compounds and other agents permit us to exclude a release of neuromediators or a direct stimulation of post‐synaptic receptors to account for the rhythmic effect of B25 in the rat vas deferens. 3 In the same tissue, the increase in 45Ca2+ uptake, the voltage‐dependency as well as the dependence of the B25‐induced rhythmic activity upon the external calcium concentration indicate a direct activation of voltage‐sensitive calcium channels (VSCC). 4 Verapamil paradoxically stimulated the rhythmic effect of B25 in the rat vas deferens. La3+ was inactive while nifedipine was a weak inhibitor. By contrast Ni2+ and Mn2+ ions were good inhibitors (IC50 < 10−4m), suggesting that a possible opening of T‐type VSCC underlies the rhythmic effect of B25. 5 In radioligand binding studies competition experiments with [3H]‐nitrendipine indicated that only at high concentrations was B25 able to interact with dihydropyridine‐sensitive binding sites of heart and vas deferens smooth muscle. 6 B25 (3–30 μm) counteracted the inhibitory effects of ω‐conotoxin GVIA in field‐stimulated rat vas deferens.