Simone Ferderbar

Biomarkers of oxidative stress and endothelial dysfunction in glucose intolerance and diabetes mellitus

OBJECTIVES To evaluate biomarkers of endothelial dysfunction and oxidative stress in glucose intolerance (GI) compared to overt diabetes (DM2). DESIGN AND METHODS 140 volunteers including 96 with DM2, 32 with GI and 12 controls (C) were studied. (*)NO metabolites, (*)NO synthase inhibitors, thiols and N-acetyl-beta-glucosaminidase (NAGase) activity were analyzed by chemiluminescence, capillary electrophoresis, ELISA and colorimetric assay, respectively. RESULTS (*)NO metabolites were higher in GI (NOx: p=0.03; S-nitrosothiols: p=0.001) and DM2 (p=0.006; p=0.0006) groups in relation to group C, while nitrotyrosine was higher only in the DM2 group in comparison to the other groups. NAGase activity was elevated in GI (p=0.003) and DM2 (p=0.0004) groups in relation to group C, as well as, ADMA (p=0.01; p=0.003) and GSSG (p=0.01; p=0.002). CONCLUSIONS (*)NO metabolites, (*)NO synthase inhibitors, thiols and NAGase are biomarkers suitable to indicate endothelial dysfunction and oxidative stress in the early stages of impaired response to insulin.

Cholesterol oxides as biomarkers of oxidative stress in type 1 and type 2 diabetes mellitus

Oxidative stress plays an important role in the pathophysiology of diabetes mellitus. The aim of this study was to evaluate the formation of cholesterol oxides (ChOx) as biomarkers of oxidative stress in subjects with impaired glucose tolerance (IGT) and diabetes.

Hypoxia Inducible Factor–Dependent Regulation of Angiogenesis by Nitro–Fatty Acids

Objective—Nitro-fatty acids (NO2-FAs) are emerging as a new class of cell signaling mediators. Because NO2-FAs are found in the vascular compartment and their impact on vascularization remains unknown, we aimed to investigate the role of NO2-FAs in angiogenesis. Methods and Results—The effects of nitrolinoleic acid and nitrooleic acid were evaluated on migration of endothelial cell (EC) in vitro, EC sprouting ex vivo, and angiogenesis in the chorioallantoic membrane assay in vivo. At 10 &mgr;mol/L, both NO2-FAs induced EC migration and the formation of sprouts and promoted angiogenesis in vivo in an NO-dependent manner. In addition, NO2-FAs increased intracellular NO concentration, upregulated protein expression of the hypoxia inducible factor-1&agr; (HIF-1&agr;) transcription factor by an NO-mediated mechanism, and induced expression of HIF-1&agr; target genes, such as vascular endothelial growth factor, glucose transporter-1, and adrenomedullin. Compared with typical NO donors such as spermine-NONOate and deta-NONOate, NO2-FAs were slightly less potent inducers of EC migration and HIF-1&agr; expression. Short hairpin RNA–mediated knockdown of HIF-1&agr; attenuated the induction of vascular endothelial growth factor mRNA expression and EC migration stimulated by NO2-FAs. Conclusion—Our data disclose a novel physiological role for NO2-FAs, indicating that these compounds induce angiogenesis in an NO-dependent mechanism via activation of HIF-1&agr;.

Lipid peroxidation and nitric oxide inactivation in postmenopausal women

OBJECTIVE To assess the effect of endogenous estrogens on the bioavailability of nitric oxide (.NO) and in the formation of lipid peroxidation products in pre- and postmenopausal women. METHODS NOx and S-nitrosothiols were determined by gaseous phase chemiluminescence, nitrotyrosine was determined by ELISA, COx (cholesterol oxides) by gas chromatography, and cholesteryl linoleate hydroperoxides (CE18:2-OOH), trilinolein (TG18:2-OOH), and phospholipids (PC-OOH) by HPLC in samples of plasma. RESULTS The concentrations of NOx, nitrotyrosine, COx, CE18:2-OOH, and PC-OOH were higher in the postmenopausal period (33.8+/-22.3 microL; 230+/-130 nM; 55+/-19 ng/microL; 17+/-8.7 nM; 2775+/-460 nM, respectively) as compared with those in the premenopausal period (21.1+/-7.3 microM; 114+/-41 nM; 31+/-13 ng/microL; 6+/-1.4 nM; 1635+/-373 nM). In contrast, the concentration of S-nitrosothiols was lower in the postmenopausal period (91+/-55 nM) as compared with that in the premenopausal p in the premenopausal period (237+/-197 nM). CONCLUSION In the postmenopausal period, an increase in nitrotyrosine and a reduction of S-nitrosothiol formation, as well as an increase of COx, CE18:2-OOH and PC-OOH formation occurs. Therefore, NO inactivation and the increase in lipid peroxidation may contribute to endothelial dysfunction and to the greater risk for atherosclerosis in postmenopausal women.

Bioactivity of nitrolinoleate: effects on adhesion molecules and CD40–CD40L system

The vascular effects of nitrolinoleate (LNO2), an endogenous product of linoleic acid (LA) nitration by nitric oxide-derived species and a potential nitrosating agent, were investigated on rat endothelial-leukocyte interactions. Confocal microscopy analysis demonstrated that LNO2 was capable to deliver free radical nitric oxide (*NO) into cells, 5 min after its administration to cultured cells, with a peak of liberation at 30 min. THP-1 monocytes incubated with LNO2 for 5 min presented nitrosation of CD40, leading to its inactivation. Other anti-inflammatory actions of LNO2 were observed in vivo by intravital microscopy assays. LNO2 decreased the number of adhered leukocytes in postcapillary venules of the mesentery network. In addition to this, LNO2 reduced mRNA and protein expression of beta2-integrin in circulating leukocytes, as well as VCAM-1 in endothelial cells isolated from postcapillary venules, confirming its antiadhesive effects on both cell types. Moreover, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a nitric oxide scavenger, partially abolished the inhibitory action of LNO2 on leukocyte-endothelium interaction, suggesting that the antiadhesion effects of LNO2 involve a dual role in leukocyte adhesion, acting as a nitric oxide donor as well as through nitric oxide-independent mechanisms. In conclusion, LNO2 inhibited adhesion molecules expression and promoted *NO inactivation of the CD40-CD40L system, both important processes of the inflammatory response.

Efecto del Propóleos Chileno sobre el Metabolismo de Glucosa en Ratones Diabéticos

En el presente estudio se evaluo el efecto del propoleos sobre el metabolismo de la glucosa en ratones C57/BL-6 con diabetes mellitus tipo 2 inducida por dieta alta en grasa. Se midieron los cambios en las concentraciones sericas de lipidos, glucosa e insulina, y el efecto sobre la captacion de 2-deoxi-[2,6-3H]-D-glucosa, sintesis de [14C]-glicogeno y descarboxilacion de [U-14C]-D-glucosa inducida por insulina en musculo aislado. Los resultados muestran que en ratones diabeticos, el tratamiento con propoleos (150 mg/kg/dia) reduce los niveles de insulina e indice HOMA (P<0.05). Tambien disminuyo la obesidad abdominal de estos animales (P<0.05). Por otro lado, no modifico las concentraciones plasmaticas de glucosa, colesterol total y trigliceridos. Se observo tambien que la captacion de 2-deoxi-[2,6-3H]-D-glucosa, sintesis de [14C]-glicogeno y descarboxilacion de [U-14C]-D-glucosa inducida por insulina en musculo soleo de ratones tratados con propoleos fue significativamente superior al grupo control (P<0.05). En resumen, nuestros datos confirman que el propoleos es capaz de modular el metabolismo de glucosa en ratones C57/BL-6 con diabetes mellitus tipo 2 inducida por dieta alta en grasa. Los datos obtenidos constituyen un importante antecedente que avala el posible uso del propoleos como fuente de polifenoles con actividad antidiabetogenica.