Semicarbazide-sensitive Amine Oxidase Activity Research Articles

Skin wound healing: some biochemical parameters in guinea-pig.

Hairs were removed from the dorsal skin of guinea-pigs and 5-6 wounds (7 x 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Monoamine oxidase activities in dissociated cell fractions from rat skeletal muscle.

Collagenase was used to dissociate rat skeletal muscle (gastrocnemius) into its constituent cells, from which a myocyte fraction enriched in striated muscle cells, and a non-myocyte fraction containing cells of connective tissue and vascular origin, were prepared. The activities of amine oxidase enzymes and alkaline phosphatase (AP) were then assayed in these fractions, and also in homogenates prepared from corresponding samples of non-dissociated tissue. The specific activities of the semicarbazide-sensitive amine oxidase (SSAO) and AP were considerably higher (30 to 35-fold) in non-myocyte than in myocyte fractions. AP is generally considered to be present predominantly in vascular cells of skeletal muscle, with little, if any, in skeletal muscle cells themselves. Thus, the results obtained may indicate a similar localization for SSAO activity. Support for this came from histochemical studies, which showed staining for SSAO primarily over the walls of larger blood vessels in the muscle. Unlike SSAO and AP, were marked differences in MAO-A activity between myocyte and non-myocyte fractions were not found, suggesting that MAO-A is more probably a constituent of cells within both fractions.

The Enhanced Daily Excretion of Urinary Methylamine in Rats Treated with Semicarbazide or Hydralazine May Be Related to the Inhibition of Semicarbazide-sensitive Amine Oxidase Activities

The effects of amine oxidase inhibitors upon the daily urinary excretion of monomethylamine (MMA), dimethylamine (DMA), trimethylamine (TMA) and ammonia in the rat have been examined. Administration of hydralazine (5 mg kg-1) or semicarbazide (100 mg kg-1), drugs which irreversibly inhibit semicarbazide-sensitive amine oxidases (SSAO) but not monoamine oxidase (MAO), enhanced MMA excretion by around three- to six-fold above pretreatment levels, whereas no effect of pargyline (25 mg kg-1), a selective irreversible inhibitor of MAO was found. No apparent changes in DMA or TMA excretion in response to drug-treatment were observed. Ammonia excretion also was generally unchanged except for an apparent marked increase (approximately four-fold) over the 24 h following semicarbazide, a result which might be explained if ammonia is a degradation product of semicarbazide metabolism in the rat. With recent evidence that MMA is a substrate in-vitro for SSAO activities, results here may indicate that SSAO or related enzymes are involved in endogenous MMA turnover.

Age-related changes in monoamine oxidase and semicarbazide-sensitive amine oxidase activities of rat aorta.

Aorta MAO-A and SSAO activities were measured on young (3 months) and old (23-26 months) rats. A significant decrease (30-40%) in SSAO activity was found with benzylamine as substrate and the decrease was due to a reduction in Vmax. No significant changes in MAO-A activity were found in the aorta of old rats. beta-PEA is oxidized mainly by SSAO in rat aorta. However, the significance of this is unclear since the physiological role of that enzyme remains unknown.

Effect of Pyridoxamine on Semicarbazide-sensitive Amine Oxidase Activity of Rabbit Lung and Heart

Rabbit lung and heart show clorgyline-resistant benzylamine oxidase activity which is sensitive to semicarbazide (SSAO) and alpha-amino-guanidine. This SSAO activity is inhibited by pyridoxamine with an IC50 of 6.3 x -6 M for lung and of 1.1 x 10(-5) M for heart, the inhibition being non-competitive and only partially reversed by dialysis at 4 degrees C. Semicarbazide, alpha-aminoguanidine and pyridoxamine show a similar time-dependent type of inhibition of rabbit lung and heart SSAO.

S45-03 - Biochemical and biophysical aspects of the pathophysiology of first episode of schizophrenia

IntroductionThe knowledge of pathophysiology of first psychotic episode is still fragmentary.AimTo investigate some biochemical and biophysical parameters in first-episode, drug-naive schizophrenic (FES) patients.Methods26 FES patients (ICD-10; F 20.0 and F 20.3) and 15 age-and gender-match volunteers were investigated. Clinical severity of FES patients were assessed by PANSS scale. Platelet monoamine oxidase (MAO) and serum semicarbazide-sensitive amine oxidase (SSAO) activities, middle-mass endotoxic molecules (MMEM) and malondialdehyde (MDA) levels were measured using respective methods. Steady-state and subnanosecond fluorescent spectroscopy were used for the investigation of albumin conformational changesResults Severity of disorder prior the treatment was 75.5 ± 2.2 (PANSS score). FES patients were characterized by significant increase in MAO activity (99%) and MMEM concentration (124%) and significant decrease in SSAO activity (26%) as compared with controls. Changes of albumin conformational and functional parameters (“effective” albumin concentration and“reserve” of albumin binding) estimated by steady-state fluorescent spectroscopy were insignificant. Factor analysis revealed that MAO and SSAO are more tightly connected with pathogenetic mechanisms of FES then MMEM, MDA and albumin functional parameters. Significant conformational changes of albumin of FES patients were detected using pulse fluorescent spectroscopy with subnanosecond resolution. Results are compared with the data received in chronic schizophrenic patients.ConclusionFrom pathophysiological point of view FES is the initial step in development of pathologically disturbed biochemical status characteristic to chronic schizophrenia.The study was supported by grant # 3156 from International Science and Technology Center (ISTC).

P03-348 - Biochemical and biophysical aspects of the pathophysiology of first episode of schizophrenia

IntroductionThe knowledge of pathophysiology of first psychotic episode is still fragmentary.AimTo investigate some biochemical and biophysical parameters in first-episode, drug-naive schizophrenic (FES) patients.Methods26 FES patients (ICD-10; F 20.0 and F 20.3) and 15 age-and gender-match volunteers were investigated. Clinical severity of FES patients were assessed by PANSS scale. Platelet monoamine oxidase (MAO) and serum semicarbazide-sensitive amine oxidase (SSAO) activities, middle-mass endotoxic molecules (MMEM) and malondialdehyde (MDA) levels were measured using respective methods. Steady-state and subnanosecond fluorescent spectroscopy were used for the investigation of albumin conformational changes.ResultsSeverity of disorder prior the treatment was 75.5 ± 2.2 (PANSS score). FES patients were characterized by significant increase in MAO activity (99%) and MMEM concentration (124%) and significant decrease in SSAO activity (26%) as compared with controls. Changes of albumin conformational and functional parameters (“effective” albumin concentration and “reserve” of albumin binding) estimated by steady-state fluorescent spectroscopy were insignificant. Factor analysis revealed that MAO and SSAO are more tightly connected with pathogenetic mechanisms of FES then MMEM, MDA and albumin functional parameters. Significant conformational changes of albumin of FES patients were detected using pulse fluorescent spectroscopy with subnanosecond resolution. Results are compared with the data received in chronic schizophrenic patients.ConclusionFrom pathophysiological point of view FES is the initial step in development of pathologically disturbed biochemical status characteristic to chronic schizophrenia. The study was supported by grant # 3156 from International Science and Technology Center (ISTC).

P03-243 - Disturbance of neurotransmitters monoamines and indices of reducing-oxidizing processes in patient with the first episode of schizophrenia (FES)

IntroductionEffective treatment of FES patients may lead to achievement of long-term remission, decrease the number of relapses and increase the level of social activity and quality of life.AimTo study some pathophysiological mechanisms of FES.MethodsThe group of patients who were investigated clinically and biochemically consists of 26 persons (11 women and 15 men, average age 28.2 ± 9.5 years) with the first psychotic episode (F20.0; F20.3). Some biochemical parameters, representing the monoaminergic systems, and some biophysical parameters, representing reducing-oxidizing processes, were investigated. These parameters in all patients were estimated following the admission and prior to any treatment.ResultsThe severity of the disorder on admission to the clinic according to PANSS score was 75,5 ± 2,2 (i.e., moderately severe). Patients with FES were characterized by a significant increase of platelet momnoamine oxidase activity (by 107%; р < 0,01) and decrease of serum semicarbazide-sensitive amine oxidase activity (by 29%; p < 0,001) in comparison to the controls. Both reactive capability of SH-group (Cys-34 residue) of serum albumin, the main source of thiols of plasma and intersticial fluid, measured in reaction with thiol-specific reagent - dithyonitrobenzoic acide, and kinetic coefficient were decreased in FES patients (by 24%; p = 0,02) in comparison to controls.ConclusionThese results show that FES patients are characterized by pronounced metabolic disturbances.

Inhibition of semicarbazide-sensitive amine oxidase attenuates myocardial ischemia–reperfusion injury in an in vivo rat model

Aims This study tested the hypothesis that the inhibition of semicarbazide-sensitive amine oxidase (SSAO) after ischemia could attenuate myocardial ischemia–reperfusion (I/R) injury. Main methods Anesthetized male Sprague–Dawley rats underwent myocardial I/R injury. Saline, semicarbazide (SCZ, 30 mg/kg), hydralazine (HYD, 10 mg/kg), or LJP 1207 (30 mg/kg) was administered intraperitoneally 3 min before reperfusion. After 30 min of ischemia and 180 min of reperfusion, the myocardial infarct size was determined using nitroblue tetrazolium staining. Myocardial myeloperoxidase activity was determined through biochemical assay. HE staining was used for histopathological evaluation. Myocardial SSAO activity was assayed with high performance liquid chromatography analysis. Additionally, the endothelial expression of P-selectin was evaluated using immunohistochemistry after 30 min of ischemia and 20 min of reperfusion. Key findings Myocardial SSAO activity was increased in myocardial I/R injury. Administration of SCZ, HYD, or LJP 1207 reduced the myocardial infarct size and decreased leukocyte infiltration and endothelial P-selectin expression in myocardial I/R injury in vivo. Significance These data suggest that myocardial I/R injury up-regulates myocardial SSAO activity, and the inhibition of SSAO prior to reperfusion is able to attenuate acute myocardial I/R injury.

Plasma VAP-1/SSAO Activity Predicts Intracranial Hemorrhages and Adverse Neurological Outcome After Tissue Plasminogen Activator Treatment in Stroke

Vascular adhesion protein-1 (VAP-1) is a cell surface and circulating enzyme involved in recruitment of lymphocytes and neutrophils through its semicarbazide-sensitive amine oxidase (SSAO) activity. We aimed to study plasma VAP-1/SSAO activity in relation to the risk for intracranial bleeding complications in patients with stroke treated with tissue plasminogen activator (tPA), the greatest safety concern with this treatment. In 141 patients with ischemic stroke, we measured VAP-1/SSAO activity in plasma taken before tPA administration. Hemorrhagic events were classified according to brain CT criteria and functional outcomes evaluated using the National Institutes of Health Stroke Scale. We also assessed the potential therapeutic effect of blocking VAP-1/SSAO activity in a rat embolic stroke model treated with tPA. We saw significantly higher levels of plasma VAP-1/SSAO activity in patients who subsequently experienced hemorrhagic transformation. Elevated plasma VAP-1/SSAO activity also predicted worse neurological outcome in these patients. In the rat model, we confirmed that use of the inhibitor semicarbazide prevented adverse effects caused by delayed tPA administration, leading to a smaller infarct volume. Our data demonstrate that baseline VAP-1/SSAO activity predicts parenchymal hemorrhage after tPA, suggesting the safety of thrombolytic agents could be improved by considering VAP-1/SSAO activity. Furthermore, anti-VAP-1/SSAO drugs given with tPA may prevent neurological worsening in patients with ischemic stroke.

An Electrocatalytic System that Mimics the Catalytic Oxidation of Biogenic Mono- and Polyamines by Semicarbazide-sensitive Amine Oxidases (SSAOs)

Chemoselective oxidation of primary aliphatic biogenic mono- and polyamines into imines has been successfully achieved, under metal-free conditions, by using an electrocatalytic system that mimics the activity of semicarbazide-sensitive amine oxidase (SSAO) enzymes. Accordingly, high catalytic performance was observed with unbranched primary amines such as methylamine and aminoacetone, and with the primary amino groups of diamines and polyamines like putrescine and spermidine, all of them being reference substrates for SSAO enzymes. Furthermore, contrary to flavin-adenine dinucleotide (FAD)-dependent amine oxidase enzymes, no activity was found with secondary and tertiary amines. Finally, when compared with the direct electrochemical oxidation of primary aliphatic amines, which occurs at high anodic potential (Ean > + 1.5 V vs SCE) and led to unstable cation radicals that rapidly deprotonate and attach to the electrode surface (Pt, carbon), 1.0 V was gained using this electrocatalytic process (Ean = + 0.5 V vs SCE).

Modulation of Endothelium-Dependent Relaxation of Equine Digital Arteries By Insulin and Hypoxia

Modulation of Endothelium-Dependent Relaxation of Equine Digital Arteries By Insulin and Hypoxia

Changes in the activities of semicarbazide-sensitive amine oxidase in inferior mesenteric artery segments and in serum of patients with type 2 diabetes

This study aimed to evaluate the semicarbazide-sensitive amine oxidase (SSAO) activity in human arterial tissues and in serum of patients with type 2 diabetes. The SSAO activity, with (14)C-benzylamine as substrate, was measured in homogenates of human inferior mesenteric arteries obtained at surgery, from 10 patients with type 2 diabetes and 16 non-diabetic patients and in the serum of 39 patients with type 2 diabetes and 40 non-diabetic control patients. The SSAO activity in the homogenates of vascular tissue was significantly lower in the diabetics than in the non-diabetics (P = 0.001). The SSAO activity in the serum of patients with type 2 diabetes was higher when compared with control group (P = 0.0001). In conclusion, the SSAO activity increased in the serum and decreased in the arterial tissue. These findings suggest damage in the vascular tissue and support the hypothesis that serum SSAO may be a useful biochemical marker for diabetes.

First episode of schizophrenia is accompanied by changes in the activity of blood amine oxidases

In 26 patients with their first episode of schizophrenia, we measured the activity of platelet monoamine oxidase and semicarbazide-sensitive amine oxidase of the blood serum. The severity of the disease was evaluated as moderate (over 75 points according to PANSS scale). In these patients we found a significantly increased activity of monoamine oxidase (by 107%) and significantly decreased activity of semicarbazide-sensitive amine oxidase (by 29%), as compared to healthy volunteers. The results of factor analysis suggest that these two enzymes may be integral components of the pathogenetic mechanisms of the first episode of schizophrenia.

Elevated activity of semicarbazide-sensitive amine oxidase in blood from patients with skeletal metastases of prostate cancer

Elevated activity of semicarbazide-sensitive amine oxidase in blood from patients with skeletal metastases of prostate cancer

Vascular adhesion protein-1 regulates leukocyte transmigration rate in the retina during diabetes

Vascular adhesion protein-1 (VAP-1) is an endothelial adhesion molecule that possesses semicarbazide-sensitive amine oxidase (SSAO) activity and is involved in leukocyte recruitment. Leukocyte adhesion to retinal vessels is a predominant feature of experimentally induced diabetic retinopathy (DR). However, the role of VAP-1 in this process is unknown. Diabetes was induced by i.p. injection of Streptozotocin in Long–Evans rats. The specific inhibitor of VAP-1, UV-002, was administered by daily i.p. injections. The expression of VAP-1 mRNA in the retinal extracts of normal and diabetic animals was measured by real-time quantitative polymerase chain reaction (PCR). Firm leukocyte adhesion was quantified in retinal flatmounts after intravascular staining with concanavalin A (ConA). Leukocyte transmigration rate was quantified by in vivo acridine orange leukocyte staining (AOLS). In diabetic rats, the rate of leukocyte transmigration into the retinal tissues of live animals was significantly increased, as determined by AOLS. When diabetic animals were treated with daily injections of the VAP-1 inhibitor (0.3 mg/kg), leukocyte transmigration rate was significantly reduced (P < 0.05). However, firm adhesion of leukocytes in diabetic animals treated with the inhibitor did not differ significantly from vehicle-treated diabetic controls. This work provides evidence for an important role of VAP-1 in the recruitment of leukocyte to the retina in experimental DR. Our results reveal the critical contribution of VAP-1 to leukocyte transmigration, with little impact on firm leukocyte adhesion in the retinas of diabetic animals. VAP-1 inhibition might be beneficial in the treatment of DR.

Comparison of the effects of semicarbazide and β-aminopropionitrile on the arterial extracellular matrix in the Brown Norway rat

To investigate a putative role for semicarbazide-sensitive amine oxidase (SSAO) in arterial extracellular matrix (ECM) organization, we compared arteries of growing Brown Norway (BN) rats after chronic administration of semicarbazide (SCZ) and β-aminopropionitrile (BAPN), two inhibitors with different properties and relative specificities for SSAO and lysyl oxidase (LOX). The BN model is particularly well adapted to evaluating effects of toxic compounds on the arterial elastic network. We measured aortic LOX and SSAO activities and quantified several ECM parameters. After a pilot study comparing doses previously studied and testing for additivity, we studied low and high equimolar doses of SCZ and BAPN. Both compounds similarly inhibited LOX, whereas SCZ inhibited SSAO far more effectively than BAPN. Both decreased carotid wall rupture pressure, increased tail tendon collagen solubility, decreased aortic insoluble elastin (% dry weight) and dose-dependently increased defects in the internal elastic lamina of abdominal aorta, iliac and renal arteries. Our results suggest that either these effects are mediated by LOX inhibition, SCZ being slightly more effective than BAPN in our conditions, or SSAO acts similarly to and in synergy with LOX on ECM, the greater SCZ effect reflecting the simultaneous inhibition of both enzymes. However, the high SCZ dose increased aortic collagen and ECM proteins other than insoluble elastin markedly more than did equimolar BAPN, possibly revealing a specific effect of SSAO inhibition. To discriminate between the two above possibilities, and to demonstrate unequivocally a specific effect of SSAO inhibition on ECM formation or organization, we must await availability of more specific inhibitors.

Influence of prolonged fasting on monoamine oxidase and semicarbazide-sensitive amine oxidase activities in rat white adipose tissue

Monoamine oxidase (MAO) and semicarbazide-sensitive amine oxidase (SSAO) activities are very high in white adipose tissue (WAT). SSAO, also known as Vascular Adhesion Protein-1 in vessels, is present at the surface of fat cells and independent approaches have evidenced its impressive increase during adipogenesis. However, the factors that might regulate the expression SSAO and MAO in adipose tissue are still poorly defined. Here, we report the influence of fasting on MAO and SSAO activities in adipose depots. A decrease of MAO activity occurred after three days of starvation in the intra-abdominal adipose tissue (INWAT) of male Wistar rats, regardless of their initial adiposity or fat loss. The reduced fat stores of seven-week old rats, loosing 59 % of INWAT mass during fasting, contained only one half of the MAO activity found in fed control. The same reduction of MAO was observed after prolonged fasting in older rats which lose only 26% of their INWAT during the same starvation duration, leading to a fat mass comparable to that of younger fed control rats. It was therefore the endocrine and metabolic changes occurring during fasting that were responsible for the reduced MAO activity and not the amount of INWAT. Surprisingly, SSAO activity remained unchanged during starvation. In subcutaneous WAT, the changes in MAO and SSAO activities exhibited the same tendencies than those found in INWAT. Taken together, these data show that both MAO and SSAO activities increase in INWAT with age-dependent fattening, and indicate that only MAO diminishes during fasting.

I024 Comparison of the effects of semicarbazide and beta-aminopropionitrile on arteries in the brown norway rat

Semicarbazide-sensitive amine oxidase (SSAO) is highly expressed by the smooth muscle cells of the aorta but its function within the arterial wall is unknown. This contrasts with another lifeessential amine oxidase expressed in the aortic wall, lysyl oxidase (LO), responsible for post-translational cross-linking of tropoelastin and collagen molecules to produce insoluble, highly mechanically resistant fibres. It has been hypothesized that SSAO may participate in extracellular matrix cross-linking, but proof is lacking. To investigate whether SSAO may play such a role physiologically, we compared effects of semicarbazide (SCZ) and β-aminopropionitrile (BAPN), two amine oxidase inhibitors with different properties and relative specificities for SSAO and LO, on arteries in growing Brown Norway rats, which present a rare phenotype of spontaneous rupture of the internal elastic lamina (IEL) that is aggravated by LO inhibition. We measured aortic LO and SSAO activities during and at the end of 8-9 weeks of treatment, started at weaning, and quantified aortic insoluble elastin and total collagen contents, IEL ruptures in several arteries, ex vivo carotid artery wall rupture pressure and solubility of tail tendon collagen. After a pilot study using equivalent doses by weight, and combining the two compounds to test for additivity, we performed a study using low and high equimolar doses of SCZ and BAPN. Both compounds similarly inhibited LO, whereas SCZ was far more effective than BAPN in inhibiting SSAO. Both compounds decreased carotid rupture pressure, increased collagen solubility, decreased aortic insoluble elastin (% dry weight) and also increased IEL ruptures in abdominal aorta, iliac, renal and caudal arteries in a dose-dependent manner. The high dose of SCZ increased aortic collagen and extracellular proteins other than insoluble elastin markedly more than did equimolar BAPN, possibly revealing a specific effect of SSAO inhibition. We conclude that the majority of SCZ effects are mediated by LO inhibition, SCZ being more effective than BAPN in our in vivo experimental conditions, and to demonstrate unequivocally a specific effect of SSAO inhibition on extracellular matrix formation or organization, we must await availability of more specific inhibitors.

Flaxseed protein-derived peptide fractions: Antioxidant properties and inhibition of lipopolysaccharide-induced nitric oxide production in murine macrophages

A protein isolate was produced from cellulase-treated defatted flaxseed meal followed by hydrolysis with seven proteases and evaluation of the hydrolysates for antioxidant and anti-inflammatory properties. The flaxseed protein hydrolysates (FPH) were processed by ultrafiltration and ion-exchange chromatography to isolate low molecular weight (LMW) and cationic peptide fractions, respectively. The peptides showed antioxidant properties in scavenging 2,2-diphenyl-1-picrylhydrazyl radical, superoxide anion radical, electron-spin resonance-detected hydroxyl radical and nitric oxide. In addition, all peptide fractions inhibited semicarbazide-sensitive amine oxidase activity. Antioxidant activities of these peptides were dependent on the specificity of proteases and size of the resulting peptides. The LMW fractions from pepsin, ficin and papain FPH also inhibited lipopolysaccharide-induced nitric oxide productions in RAW 264.7 macrophages without apparent cytotoxicity; thus, these peptides may act as anti-inflammatory agents. Thus, flaxseed protein hydrolysates may serve as potential ingredients for the formulation of therapeutic products.