Semicarbazide-sensitive Amine Oxidase Activity Research Articles

Inactivation of semicarbazide-sensitive amine oxidase induces the phenotypic switch of smooth muscle cells and aggravates the development of atherosclerotic lesions

Background and aimsClinical studies have demonstrated that serum semicarbazide-sensitive amine oxidase (SSAO) activities positively correlate with the progression of atherosclerosis. The aim of the present study is to investigate the effect of SSAO inactivation on the development of atherosclerosis. MethodsFemale LDLr knockout (KO) mice were given the Western-type diet for 6 and 9 weeks to induce the formation of early and advanced lesions, and semicarbazide (SCZ, 0.125%) was added into the drinking water to inactivate SSAO in vivo. ResultsDespite no impact on plasma total cholesterol levels, abrogation of SSAO by SCZ not only resulted in the enlargement of both early (1.5-fold, p = 0.0043) and advanced (1.8-fold, p = 0.0013) atherosclerotic lesions, but also led to reduced/increased lesion contents of macrophages/smooth muscle cells (SMCs) (macrophage: ∼0.74-fold, p = 0.0002(early)/0.0016(advanced); SMC: ∼1.55-fold, p = 0.0003(early)/0.0001(advanced)), respectively. Moreover, SSAO inactivation inhibited the migration of circulating monocytes into peripheral tissues and reduced the amount of circulating Ly6Chigh monocytes (0.7-fold, p = 0.0001), which may account for the reduced macrophage content in lesions. In contrast, the increased number of SMCs in lesions of SCZ-treated mice is attributed to an augmented synthetic vascular SMC phenotype switch as evidenced by the increased proliferation of SMCs and accumulation of collagens in vivo. ConclusionSSAO inactivation by SCZ promotes the phenotypic switch of SMCs and the development of atherosclerosis. The enzymatic activity of SSAO may thus represent a potential target in the prevention and/or treatment of atherosclerosis.

Amine oxidases as important agents of pathological processes of rhabdomyolysis in rats.

In this study we have tested an idea on the important role of amine oxidases (semicarbazide-sensitive amine oxidase, diamine oxidase, polyamine oxidase) as an additional source of oxidative/carbonyl stress under glycerol-induced rhabdomyolysis, since the enhanced formation of reactive oxygen species and reactive carbonyl species in a variety of tissues is linked to various diseases. In our experiments we used the sensitive fluorescent method devised for estimation of amine oxidases activity in the rat kidney and thymus as targeted organs under rhabdomyolysis. We have found in vivo the multiple rises in activity of semicarbazide-sensitive amine oxidase, diamine oxidase, polyamine oxidase (2-4.5 times) in the corresponding cell fractions, whole cells or their lysates at the 3-6th day after glycerol injection. Aberrant antioxidant activities depended on rhabdomyolysis stage and had organ specificity. Additional treatment of animals with metal chelator ‘Unithiol’ adjusted only the activity of antioxidant enzymes but not amine oxidases in both organs. Furthermore the in vitro experiment showed that Fenton reaction (hydrogen peroxide in the presence of iron) products alone had no effect on semicarbazide-sensitive amine oxidase activity in rat liver cell fraction whereas supplementation with methylglyoxal resulted in its significant 2.5-fold enhancement. Combined action of the both agents had additive effect on semicarbazide-sensitive amine oxidase activity. We can assume that biogenic amine and polyamine catabolism by amine oxidases is upregulated by oxidative and carbonyl stress factors directly under rhabdomyolysis progression, and the increase in catabolic products concentration contributes to tissue damage in glycerol-induced acute renal failure and apoptosis stimulation in thymus.

Expression of the semicarbazide-sensitive amine oxidase in articular cartilage: its role in terminal differentiation of chondrocytes in rat and human

Semicarbazide-sensitive amine oxidase (SSAO) catalyzes the oxidation of primary amines into ammonia and reactive species (hydrogen peroxide, aldehydes). It is highly expressed in mammalian tissues, especially in vascular smooth muscle cells and adipocytes, where it plays a role in cell differentiation and glucose transport. The study aims at characterizing the expression and the activity of SSAO in rat and human articular cartilage of the knee, and to investigate its potential role in chondrocyte terminal differentiation. SSAO expression was examined by immunohistochemistry and western blot. Enzyme activity was measured using radiolabeled benzylamine as a substrate. Primary cell cultures of rat chondrocytes were treated for 21 days by a specific SSAO inhibitor, LJP 1586. Terminal chondrocyte differentiation markers were quantified by RT-qPCR. The basal and IL1β-stimulated glucose transport was monitored by the entrance of (3)[H]2-deoxyglucose in chondrocytes. SSAO was expressed in chondrocytes of rat and human articular cartilage. SSAO expression was significantly enhanced during the hypertrophic differentiation of chondrocytes characterized by an increase in MMP13 and in alkaline phosphatase (ALP) expressions. SSAO inhibition delayed the late stage of chondrocyte differentiation without cell survival alteration and diminished the basal and IL1β-stimulated glucose transport. Interestingly, SSAO activity was strongly increased in human osteoarthritic cartilage. SSAO was expressed as an active form in rat and human cartilage. The results suggest the involvement of SSAO in rat chondrocyte terminal differentiation via a modulation of the glucose transport. In man, the increased SSAO activity detected in osteoarthritic patients may trigger hypertrophy and cartilage degeneration.

Brain Formaldehyde is Related to Water Intake behavior.

A promising strategy for the prevention of Alzheimer’s disease (AD) is the identification of age-related changes that place the brain at risk for the disease. Additionally, AD is associated with chronic dehydration, and one of the significant changes that are known to result in metabolic dysfunction is an increase in the endogenous formaldehyde (FA) level. Here, we demonstrate that the levels of uric formaldehyde in AD patients were markedly increased compared with normal controls. The brain formaldehyde levels of wild-type C57 BL/6 mice increased with age, and these increases were followed by decreases in their drinking frequency and water intake. The serum arginine vasopressin (AVP) concentrations were also maintained at a high level in the 10-month-old mice. An intravenous injection of AVP into the tail induced decreases in the drinking frequency and water intake in the mice, and these decreases were associated with increases in brain formaldehyde levels. An ELISA assay revealed that the AVP injection increased both the protein level and the enzymatic activity of semicarbazide-sensitive amine oxidase (SSAO), which is an enzyme that produces formaldehyde. In contrast, the intraperitoneal injection of formaldehyde increased the serum AVP level by increasing the angiotensin II (ANG II) level, and this change was associated with a marked decrease in water intake behavior. These data suggest that the interaction between formaldehyde and AVP affects the water intake behaviors of mice. Furthermore, the highest concentration of formaldehyde in vivo was observed in the morning. Regular water intake is conducive to eliminating endogenous formaldehyde from the human body, particularly when water is consumed in the morning. Establishing good water intake habits not only effectively eliminates excess formaldehyde and other metabolic products but is also expected to yield valuable approaches to reducing the risk of AD prior to the onset of the disease.

Hypoxia inhibits semicarbazide-sensitive amine oxidase activity in adipocytes

Semicarbazide-sensitive amine oxidase (SSAO), an enzyme highly expressed on adipocyte plasma membranes, converts primary amines into aldehydes, ammonium and hydrogen peroxide, and is likely involved in endothelial damage during the course of diabetes and obesity. We investigated whether in vitro, adipocyte SSAO was modulated under hypoxic conditions that is present in adipose tissue from obese or intensive care unit. Physical or pharmacological hypoxia decreased SSAO activity in murine adipocytes and human adipose tissue explants, while enzyme expression was preserved. This effect was time-, dose-dependent and reversible. This down-regulation was confirmed in vivo in subcutaneous adipose tissue from a rat model of hypoxia. Hypoxia-induced suppression in SSAO activity was independent of the HIF-1-α pathway or of oxidative stress, but was partially antagonized by medium acidification. Hypoxia-induced down-regulation of SSAO activity could represent an adaptive mechanism to lower toxic molecules production, and may thus protect from tissue injury during these harmful conditions.

Determination of human serum semicarbazide-sensitive amine oxidase activity via flow injection analysis with fluorescence detection after online derivatization of the enzymatically produced benzaldehyde with 1,2-diaminoanthraquinone

A fast, simple, and sensitive flow injection analysis method was developed for the measurement of semicarbazide-sensitive amine oxidase (SSAO) activity in human serum. Benzaldehyde, generated by the action of SSAO after incubation of serum with benzylamine, was derivatized with a novel aromatic aldehyde-specific reagent (1,2-diaminoanthraquinone) and the fluorescent product was measured by fluorescence detection at excitation and emission wavelengths of 390 and 570nm, respectively. Serum SSAO activity was defined as benzaldehyde (nmol) formed per milliliter serum per hour. The method was linear over SSAO activity of 0.2–150.0nmolmL−1h−1 with a detection limit of 0.06nmolmL−1h−1. The %RSD of intra-day and inter-day precision did not exceed 9.4% and the accuracy ranged from −6.5 to −0.6%. The method was applied for the determination of the serum SSAO activity in healthy controls (C, n=24) and diabetes mellitus patients (DM, n=18). It was demonstrated that the activity (mean±SE) of SSAO in diabetics sera was significantly higher than that in healthy subjects’ ones (DM; 73.3±1.8nmolmL−1h−1 vs C; 58.9±2.2nmolmL−1h−1, P<0.01).

Prenatal dietary load of Maillard reaction products combined with postnatal Coca-Cola drinking affects metabolic status of female Wistar rats.

AimTo assess the impact of prenatal exposure to Maillard reaction products (MRPs) -rich diet and postnatal Coca-Cola consumption on metabolic status of female rats. Diet rich in MRPs and consumption of saccharose/fructose sweetened soft drinks is presumed to impose increased risk of development of cardiometabolic afflictions, such as obesity or insulin resistance.MethodsAt the first day of pregnancy, 9 female Wistar rats were randomized into two groups, pair-fed either with standard rat chow (MRP-) or MRPs-rich diet (MRP+). Offspring from each group of mothers was divided into two groups and given either water (Cola-) or Coca-Cola (Cola+) for drinking ad libitum for 18 days. Oral glucose tolerance test was performed, and circulating markers of inflammation, oxidative stress, glucose and lipid metabolism were assessed.ResultsMRP+ groups had higher weight gain, significantly so in the MRP+/Cola- vs MRP-/Cola-. Both prenatal and postnatal intervention increased carboxymethyllysine levels and semicarbazide-sensitive amine oxidase activity, both significantly higher in MRP+/Cola + than in MRP-/Cola-. Total antioxidant capacity was lower in MRP+ groups, with significant decrease in MRP+/Cola + vs MRP-/Cola+. Rats drinking Coca-Cola had higher insulin, homeostatic model assessment of insulin resistance, heart rate, advanced oxidation of protein products, triacylglycerols, and oxidative stress markers measured as thiobarbituric acid reactive substances compared to rats drinking water, with no visible effect of MRPs-rich diet.ConclusionMetabolic status of rats was affected both by prenatal and postnatal dietary intervention. Our results suggest that combined effect of prenatal MRPs load and postnatal Coca-Cola drinking may play a role in development of metabolic disorders in later life.

Glitazones inhibit human monoamine oxidase but their anti-inflammatory actions are not mediated by VAP-1/semicarbazide-sensitive amine oxidase inhibition

Glitazones are peroxisome proliferator-activated receptor gamma (PPARγ) agonists widely used as antidiabetic drugs also known as thiazolidinediones. Most of them exert other effects such as anti-inflammatory actions via mechanisms supposed to be independent from PPARγ activation (e.g., decreased plasma monocyte chemoattractant protein-1 (MCP-1) levels). Recently, pioglitazone has been shown to inhibit the B form of monoamine oxidase (MAO) in mouse, while rosiglitazone and troglitazone were described as non-covalent inhibitors of both human MAO A and MAO B. Since molecules interacting with MAO might also inhibit semicarbazide-sensitive amine oxidase (SSAO), known as vascular adhesion protein-1 (VAP-1), and since VAP-1/SSAO inhibitors exhibit anti-inflammatory activity, our aim was to elucidate whether VAP-1/SSAO inhibition could be a mechanism involved in the anti-inflammatory behaviour of glitazones. To this aim, MAO and SSAO activities were measured in human subcutaneous adipose tissue biopsies obtained from overweight women undergoing plastic surgery. The production of hydrogen peroxide, an end-product of amine oxidase activity, was determined in tissue homogenates using a fluorometric method. The oxidation of 1mM tyramine was inhibited by pargyline and almost resistant to semicarbazide, therefore predominantly MAO-dependent. Rosiglitazone was more potent than pioglitazone in inhibiting tyramine oxidation. By contrast, benzylamine oxidation was only abolished by semicarbazide: hence SSAO-mediated. Pioglitazone hampered SSAO activity only when tested at 1mM while rosiglitazone was inefficient. However, rosiglitazone exhibited anti-inflammatory activity in human adipocytes by limiting MCP-1 expression. Our observations rule out any involvement of VAP-1/SSAO inhibition and subsequent limitation of leukocyte extravasation in the anti-inflammatory action of glitazones.

Dysregulated hepatic expression of glucose transporters in chronic disease: contribution of semicarbazide-sensitive amine oxidase to hepatic glucose uptake.

Insulin resistance is common in patients with chronic liver disease (CLD). Serum levels of soluble vascular adhesion protein-1 (VAP-1) are also increased in these patients. The amine oxidase activity of VAP-1 stimulates glucose uptake via translocation of transporters to the cell membrane in adipocytes and smooth muscle cells. We aimed to document human hepatocellular expression of glucose transporters (GLUTs) and to determine if VAP-1 activity influences receptor expression and hepatic glucose uptake. Quantitative PCR and immunocytochemistry were used to study human liver tissue and cultured cells. We also used tissue slices from humans and VAP-1-deficient mice to assay glucose uptake and measure hepatocellular responses to stimulation. We report upregulation of GLUT1, -3, -5, -6, -7, -8, -9, -10, -11, -12, and -13 in CLD. VAP-1 expression and enzyme activity increased in disease, and provision of substrate to hepatic VAP-1 drives hepatic glucose uptake. This effect was sensitive to inhibition of VAP-1 and could be recapitulated by H2O2. VAP-1 activity also altered expression and subcellular localization of GLUT2, -4, -9, -10, and -13. Therefore, we show, for the first time, alterations in hepatocellular expression of glucose and fructose transporters in CLD and provide evidence that the semicarbazide-sensitive amine oxidase activity of VAP-1 modifies hepatic glucose homeostasis and may contribute to patterns of GLUT expression in chronic disease.

A cross-talk between Aβ and endothelial SSAO/VAP-1 accelerates vascular damage and Aβ aggregation related to CAA-AD

An association between semicarbazide-sensitive amine oxidase (SSAO) and cerebral amyloid angiopathy (CAA) related to Alzheimer's disease (AD) has been largely postulated. Increased SSAO activity and expression have been detected in cerebrovascular tissue and plasma of AD patients, colocalizing with cerebrovascular amyloid-beta (Aβ) deposits. As an enzyme, SSAO metabolizes primary amines generating hydrogen peroxide, ammonia, and aldehydes. The ability of these products to generate oxidative stress, to enhance the advanced glycation end-product generation, to promote the Aβ aggregation in vitro, and to induce apoptosis supports its role in CAA-related vascular pathology. However, whether the SSAO increase constitutes a cause or it is a consequence of the pathologic process has not been elucidated so far. To set up the nature of this relationship, vascular cell models expressing SSAO were treated with different Aβ forms, simulating the CAA conditions in vitro. It was found that the presence of the vasculotropic Dutch-mutated Aβ1–40 increases (Aβ1–40 D) the SSAO-dependent toxicity, which is accompanied by an increase of SSAO protein availability in endothelial cell membranes. In addition, SSAO enhances Aβ1–40 D and Aβ1–42 deposition on vascular cells by both activity-dependent and -independent mechanisms. Thus, we provide evidences indicating that Aβ itself could be one of the factors inducing SSAO increase in AD, enhancing its toxic effect, and inducing the vascular dysfunction and, in turn, that SSAO stimulates Aβ deposition on the vascular walls, thereby contributing to the CAA-AD progression. Therefore, molecules inhibiting SSAO could provide an alternative treatment for preventing/delaying the progress of CAA-AD–associated vasculopathy.

Semicarbazide-sensitive amine oxidase (SSAO) inhibition ameliorates kidney fibrosis in a unilateral ureteral obstruction murine model.

Semicarbazide-sensitive amine oxidase (SSAO) is an enzyme known for its dual function in mediating inflammation and reactive oxygen species production. However, the role of SSAO inhibitors in limiting kidney fibrosis is unclear. We aimed to determine the effectiveness of a SSAO inhibitor (SSAOi; PXS4728A) as an antifibrotic agent using a 7-day unilateral ureteric obstruction (UUO) model of acute kidney fibrosis in 6- to 8-wk-old mice. The experimental groups were 1) Sham operated; 2) UUO; 3) UUO+SSAOi (2 mg/kg); 4) UUO+telmisartan, an angiotensin receptor blocker (3 mg/kg); and 5) UUO+SSAOi+telmisartan. Kidney tissue was analyzed for histological evidence of tubulointerstitial fibrosis, nitrotyrosine staining, and mRNA expression of markers associated with fibrosis and inflammation. Kidney SSAO activity was determined by radiometric [(14)C]benzylamine methodology. Our results show that SSAOi effectively suppresses UUO-mediated SSAO activity. Extracellular matrix markers, namely, fibronectin, collagen IV protein, and nitrotyrosine staining, were lower in UUO+SSAOi mice compared with untreated UUO mice. This was consistent with the attenuated mRNA expression of collagen IV and fibronectin. SSAOi effectively inhibited transforming growth factor-β1 (TGF-β1) and monocyte chemoattractant protein-1 (MCP-1) expression to a similar extent to that observed with telmisartan. Individually, SSAOi and telmisartan induced a reduction in interstitial leukocyte and macrophage accumulation. However, the combination of SSAOi and telmisartan was more effective at reducing inflammatory cell infiltration. These results demonstrate that SSAO inhibition significantly suppresses profibrotic and proinflammatory cytokine secretion, reduces oxidative stress, and limits inflammatory cell accumulation and extracellular matrix expression in an acute model of renal fibrosis.

Increased renal semicarbazide-sensitive amine oxidase activity and methylglyoxal levels in aristolochic acid-induced nephrotoxicity

AimsAristolochic acid (AA) nephrotoxicity is related to accumulation of methylglyoxal (MGO) and Nε-(carboxymethyl)lysine (CML) in the mouse kidney. We studied the activity of renal semicarbazide-sensitive amine oxidase (SSAO), a key enzyme involved in MGO generation, in AA-treated mice, and investigated nephroprotective effects produced by metformin, a MGO scavenger. MethodsMice were orally administered water or metformin for 15days (12 or 24mgkg−1day−1), and injected AA (5mgkg−1day−1) intraperitoneally for 8days starting on day 8. Renal function was studied, and histopathological examination, determination of renal SSAO activity, and measurement of MGO levels were performed. Key findingsCompared to control mice, AA-injected mice showed significant renal damage and approximately 2.7-fold greater renal SSAO activity (p<0.05). Further, compared to control treatment, administration of 12mg/kg metformin inhibited formation of renal lesions, and significantly decreased renal MGO levels (37.33±9.78 vs. 5.89±2.64μg/mg of protein, respectively, p<0.01). In the AA-treated mice, metformin also inhibited the accumulation of CML in renal tubules, but did not affect SSAO activity. SignificanceThis study is the first to show elevated renal SSAO activity in AA-treated mice, which could be involved in MGO accumulation. Moreover, MGO scavenging by metformin reduces AA nephrotoxicity. These findings suggest that reducing MGO accumulation produces nephroprotection, revealing new therapeutic strategies for the management. SSAO is a key enzyme involved in MGO generation, and consequently, inhibition of renal SSAO activity is worth investigating in AA nephrotoxicity and other renal pathologies further.

Vascular Adhesion Protein-1 Is Significantly Elevated in Heart Transplant Recipients and Chronic Heart Failure Patients With Comorbidities.

Background: VAP-1 (vascular adhesion protein-1) is a copper-containing SSAO (semi-carbazide sensitive amine oxidase) secreted by vascular smooth muscle cells, adipocytes, and endothelial cells with functional monoamine oxidase activity. The oxidation process generates harmful products that may be involved in causing atherosclerosis and vascular damage in diabetes. Elevation of SSAO activity is observed in atherosclerosis, diabetes mellitus and obesity. Taking all these data into consideration, the aim of the study was to assess VAP-1 levels and its correlations with endothelial injury markers in prevalent heart allograft recipients (n=128) and patients with chronic heart failure (n=78). Methods:Complete blood count, urea, serum lipids, fasting glucose, creatinine, were studied by standard laboratory method in the hospital central laboratory. We assessed markers of endothelial function/injury and inflammation: vWF (von Willebrand factor), TWEAK, C-Reactive Protein with commercially available assays. Results: The mean serum VAP-1 in was lower than in patients with chronic heart failure. In patients with chronic heart failure VAP-1 was related to age (0.31,p<0.01), ejection fraction-EF (r=0.23, p<0.05), presence of hypertension (r=0.28, p<0.01), presence of diabetes (r=0.31,p<0.01), TWEAK (r=0.21, p<0.05). In heart transplant recipients VAP-1 correlated with estimated glomerular filtration rate-eGFR (r=-0.19, p<0.05), age (r=0.17, p<0.05), presence of diabetes (r=0.29, p<0.01), EF (r=-0.34, p<0.01), presence of hypertension (r=0.22, p<0.05), TWEAK (r=0.17, p<0.05), NYHA class (0.33, p<0.001). In both groups of the studied patients VAP-1 was significantly higher in patients with diabetes, hypertension, and eGFR< 60 ml/min when compared to patients without diabetes, with normotension and eGFR> 60 ml/min.(all p<0.01). Concluding, VAP-1, elevated predominantly in patients with comorbidities such as diabetes, hypertension chronic kidney disease may contribute to the worse outcomes in both of the population studied. It may also contribute to the progression of atherosclerosis with its complications.

Plasma semicarbazide-sensitive amine oxidase activity in type 1 diabetes is related to vascular and renal function but not to glycaemia.

Associations of semicarbazide-sensitive amine oxidase (SSAO) activity with renal and vascular function, oxidative stress, glycaemia and diabetes complications were determined. Plasma SSAO activity in 94 type 1 diabetes (T1DM) patients, including 34 with microvascular complications T1DM CX[+], and in 96 healthy subjects (CON) was measured by production of benzaldehyde using high-performance liquid chromatography (HPLC). SSAO activity (mean ± SD) was greater in T1DM than in CON (1049 ± 294 vs 749 ± 204 mU/L; p < 0.00001) and was higher in T1DM CX[+] vs complication-free DM subjects (1148 ± 313 mU/L vs 982 ± 269 mU/L; p = 0.01). In T1DM, SSAO activity correlated with renal dysfunction [estimated glomerular filtration rate (eGFR): r = -0.44; p = 0.0001; cystatin C: r = 0.47; p = 0.0001] and markers of inflammation [soluble vascular cell adhesion molecule-1 (sVCAM-1): r = 0.41, p = 0.0001; soluble intercellular adhesion molecule-1 (sICAM-1): r = 0.33, p = 0.002] and was inversely related to small artery elasticity (SAE) (r = -0.23, p = 0.03). In CON, SSAO activity correlated with HbA1c (r = 0.26; p = 0.02). In T1DM, SSAO activity correlates with renal dysfunction, but not with glycaemia, and may promote vascular inflammation and be a therapeutic target.

VAP-1 in peritoneally dialyzed patients

VAP-1 (vascular adhesion protein-1) possesses semicarbazide-sensitive amine oxidase (SSAO) activity. It has also been found that serum VAP-1 was elevated in acute and chronic hyperglycemia and in patients with diabetes as well as in chronic kidney disease. Renalase, with possible monoamine oxidase activity, which breaks down catecholamines such as SSAO, is expressed in the endothelium as well as in the kidney. The aim of the study was to assess serum VAP-1 levels in peritoneally dialyzed (PD) patients and factors explaining its variability. This pilot study was performed on 25 peritoneally dialyzed patients, including 4 patients with type 2 diabetes. We found that the mean VAP-1 was significantly higher in chronic ambulatory peritoneal dialysis (CAPD) patients when compared to the control group (p<0.05). Dopamine was significantly lower in PD patients when compared to the healthy volunteers (p<0.05), whereas noradrenaline was significantly higher in PD patients relative to the healthy volunteers (p<0.01). There was a significant difference in the VAP-1 concentration in the group with and without residual renal function (p<0.05) as well as between 10 patients with hyperglycemia when compared to patients with normoglycemia (p<0.05). There was no effect of gender on the serum VAP-1 levels. In PD patients VAP-1 correlated with systolic blood pressure (r=-0.4, p<005), residual renal function (r=-0.62, p<0.05), and glucose (=0.54, p<0.05). We concluded that VAP-1, elevated in patients on PD, was predominantly dependent on residual kidney function and glucose level, factors both linked to endothelial damage and cardiovascular complications.

Purification and Molecular Analysis of a Monoamine Oxidase Isolated fromNarcissus tazetta

Semicarbazide-sensitive amine oxidase activity was detected in Narcissus tazetta. The enzyme was purified to homogeneity by the criterion of native polyacrylamide gel electrophoresis (PAGE) with DEAE-Sephacel, hydroxyapatite, and phenyl-Sepharose columns. The molecular mass of the enzyme, determined using a GS-520 HQ column, was estimated to be 135 kDa. SDS-PAGE yielded two bands of, 75 kDa and 65 kDa. The enzyme, which had catalytic activity for some aliphatic and aromatic monoamines, belongs to a class of monoamine oxidases (MAOs). The K(m) value for n-propylamine was 5.9 × 10⁻⁵ M. A substrate analog, 2-bromoethylamine, inhibited enzyme activity. Redox-cycling staining detected a quinone in the MAO protein. By inductively coupled plasma mass analysis, it was determined that there were 2.44 moles of copper atoms per mole of the enzyme. Protein sequence analysis revealed that there was no identity between two N-terminal residues of the 75 kDa and 65 kDa proteins of narcissus MAO.

Serum vascular adhesion protein-1 level is higher in smokers than non-smokers

Background: Semicarbazide-sensitive amine oxidase (SSAO)/vascular adhesion protein-1 (VAP-1) is involved in the pathogenesis of both atherosclerosis and cancer. Because chemical components and metabolites of cigarettes are deaminated by SSAO, the relationship between smoking and serum SSAO/VAP-1 was studied in humans.Methods: A total of 451 non-diabetic and normoalbuminuric Han Chinese subjects were recruited to participate in this study. Smoking history was obtained by using a questionnaire and those who smoked more than 100 cigarettes during a 6-month period were considered smokers. Serum VAP-1 concentration was measured by time-resolved immunofluorometric assay. Age, gender, waist circumference and estimated glomerular filtration rate (GFR) were adjusted in different statistical models.Results: Smokers were mainly male (85.7% versus 26.3%) and were more obese than non-smokers (p < 0.05). Subjects with higher serum VAP-1 concentrations were older (p < 0.001) and tended to have larger waist circumferences and lower estimated GFR. Serum VAP-1 concentration was higher in smokers than in non-smokers (p < 0.05) after adjusting for age, gender, waist circumference, estimated GFR, liver biochemistry and lipid profile.Conclusions: Cigarette smoking is associated with elevated serum VAP-1 concentration. Whether VAP-1 and its SSAO activity link the relationship between cigarette smoking, atherosclerosis and cancer requires further investigation.

Vascular Adhesion Protein-1, a Novel Molecule, in Kidney and Heart Allograft Recipients

BackgroundVAP-1 (vascular adhesion protein-1) is a copper-containing SSAO (semicarbazide-sensitive amine oxidase) secreted by vascular smooth muscle cells, adipocytes, and endothelial cells. Elevation of SSAO activity is observed in atherosclerosis, diabetes mellitus, and obesity. The aim of the study was to assess VAP-1 in prevalent heart and kidney allograft recipients. MethodsComplete blood count, urea, serum lipids, fasting glucose, and creatinine were studied by standard laboratory methods. VAP-1, N-terminal pro brain natriuretic peptide (NT-proBNP) and high-sensitivity C-reactive protein (hsCRP) were estimated using commercially available assays. ResultsHealthy volunteers showed higher hemoglobin and estimated glomerular filtration rate (eGFR) but lower creatinine, NT-proBNP, hsCRP and VAP-1 relative to heart and kidney transplantation (OHT) (KTx). Among heart transplant recipients, VAP-1 correlated with age, presence of diabetes, insulin therapy, ejection fraction, estimated glomerular filtration rate by MDRD (Modification of Diet in Renal Disease), eGFR by CKD-EPI (Chronic Kidney Disease-Epidemiological Collaboration), use of tacrolimus, LVIDd (left ventricular internal end-diastolic dimension), New York Heart Association class and NT-proBNP. VAP-1 was significantly lower among patients treated with tacrolimus than cyclosporine. Diabetic patients versus nondiabetic subjects as well as patients with eGFR below 60 versus ≥ 60 mL/min showed higher serum VAP-1 in OHT and KTx populations. Multiple regression analysis revealed VAP-1 to be predicted in 25% by LVIDd, and use of tacrolimus in OHT. In kidney transplant recipients, VAP-1 correlated only with time after transplantation and serum glucose. ConcludingVAP-1 elevations in heart transplant recipients were predominantly dependent on left ventricular diameter and use of tacrolimus; however, the precise associations with the immunosuppressive regimen warrant further studies. VAP-1 elevations in kidney transplant recipients may relate to glucose control.

Aspects of metabolic changes in first-episode drug-naïve schizophrenic patients.

Aim The aim of the study was to investigate the state of parameters characterising different sites of metabolism and the degree of endogenous intoxication in first-episode drug-naïve schizophrenic [first episode of schizophrenia (FES)] patients. It is hypothesised that the FES is the initial step in the development of pathologically disturbed biochemical status that is characteristic of chronic schizophrenia. Platelet monoamine oxidase (MAO) and serum semicarbazide-sensitive amine oxidase (SSAO) activities, serum concentrations of middle-mass endotoxic molecules (MMEM) and malondialdehyde and parameters of the serum albumin functional state were measured in 26 FES patients and 15 age-matched healthy controls. Severity of disorder before the treatment was 75.5 ± 2.2, according to Positive and Negative Syndrome Scale score. FES patients were characterised by significant increase in MAO activity (99%) and MMEM concentration (124%) and significant decrease in SSAO activity (26%) as compared with controls. Changes of all other parameters were insignificant. Regression analysis has showed a significant relationship of three parameters - MAO, SSAO and MMEM, with values of PANNS score. Two methods of extraction of factor analysis revealed that MAO and SSAO belonged to Factor 1, whereas MMEM and albumin functional parameters belonged to Factor 2. Comparing our earlier data on chronic schizophrenic patients with present data, we hypothesise that FES patients are at the stage that leads to a stable, pathological state of metabolism.

A comparison between radiometric and fluorimetric methods for measuring SSAO activity

Semicarbazide-sensitive amine oxidase (SSAO) metabolizes the oxidative deamination of primary aromatic and aliphatic amines. The final cytotoxic products of its catalysis contribute to diseases involving vascular degeneration. The increasing interest in measuring SSAO activity has led to the development of several different methods. Herein, we compare SSAO activity results obtained with radiometric and fluorimetric methods in 49 plasma samples. Although not interchangeable, a significant correlation was obtained between methods. Considering these limitations, the fluorimetric method might replace the radioisotopic one.