C. Befani

Insulin sensitivity increase after calcium supplementation and change in intraplatelet calcium and sodium-hydrogen exchange in hypertensive patients with Type 2 diabetes

Aims/hypothesis  To investigate the effect of oral calcium (Ca2+) supplementation on insulin sensitivity measured by the euglycaemic hyperinsulinaemic clamp, intraplatelet cationic concentration of Ca2+ ([Ca2+]i) and the transmembrane sodium–hydrogen exchanger (NHE) activity in erythrocytes in subjects with Type 2 diabetes and hypertension.

Prooxidant–antioxidant balance, peroxide and catalase activity in the aqueous humour and serum of patients with exfoliation syndrome or exfoliative glaucoma

BackgroundOxidative stress plays an important role in the pathobiology of exfoliation syndrome (XFS) and exfoliative glaucoma (XFG).MethodsWe investigated the prooxidant-antioxidant balance (PAB) in aqueous humour and serum samples of 20 consecutive cases of XFS, 20 of XFG, and 20 age-matched controls, employing a recently described novel assay. The activity of catalase and the levels of (hydrogen) peroxide were also measured in these samples.ResultsThere was no significant difference between the PAB in the aqueous humour of the XFS group (82.5 ± 10 AU) and age-matched control patients (78.9 ± 13.4 AU; p > 0.05). A significant shift of the PAB balance in favour of oxidants was detected in the XFG group (90.2 ± 7.6 AU) compared with controls (p  <  0.001). In the serum of patients with XFS (138.8 ± 13.2 AU) and XFG (124.08 ± 13.50 AU), PAB was significantly altered in favour of oxidants as compared to age-matched controls (114.9 ± 9.91 AU); p < 0.001). Catalase activity in the aqueous from XFS (10.1 ± 4.5 U/ml) and XFG (12.2 ± 6 U/ml) patients was significantly lower than that measured in the normal aqueous (14.6 ± 1.9 U/ml). Similarly, a significantly lower catalase activity was found in XFS (103 ± 21.4 U/ml) and XFG (116 ± 38 U/ml) serum samples compared with controls (189.6 ± 84.3 U/ml). Finally, (hydrogen) peroxide concentration in aqueous and serum samples from patients with XFS (aqueous: 26.9 ± 6.6 μM; serum: 41 ± 10 μM) and XFG (aqueous: 21.7 ± 7 μM; serum: 32 ± 4 μM) were significantly higher than that of the controls (aqueous: 9.6 ± 5.8 μM; serum: 24 ± 9 μM; p < 0.001).ConclusionsThese findings suggest that in XFS oxidative stress is counterbalanced in the aqueous, whereas the development of XFG is accompanied by a disruption of this balance in favour of oxidants.

Effect of endothelin on sodium/hydrogen exchanger activity of human monocytes and atherosclerosis-related functions.

Abstract:  The objective of this article is to investigate the influence of endothelin‐1 (ET‐1) on human monocyte Na+/H+ exchanger (NHE) activity and on the atherosclerosis‐related monocyte functions. ET‐1 caused an increase in pHi and in 22Na influx of monocytes. A reversal of ET‐1 effect on pHi was observed in the presence of the NHE1 inhibitor, cariporide. In addition, the activation of NHE1 by ET‐1 was mediated via protein kinase C (PKC), mitogen‐activated protein kinase (MAPK), phosphatidylinositol 3‐kinase (PI3K), and NADPH oxidase. Also, a link between ET‐1 and nitric oxide (NO) was observed. Furthermore, after ET‐1 treatment, an increase of the adhesive capacity, the migration ability on laminin and CD36 expression of monocytes, was observed; using cariporide this increase was abolished. Our results showed that ET‐1 induces a signaling pathway with the involvement of PKC, MAPK, PI3K, and NADPH oxidase where NHE1 plays a key role. ET‐1 also plays a significant role in atherosclerosis‐related functions of human monocytes, via NHE1 activation.

Receptor of Advanced Glycation End Products (RAGE) Positively Regulates CD36 Expression and Reactive Oxygen Species Production in Human Monocytes in Diabetes

Introduction: Advanced glycation end products (AGEs) engagement of a monocyte surface receptor (RAGE) induces atherosclerosis. AGEs also act as CD36 ligands. We studied reactive oxygen species (ROS) and CD36 expression after siRNA inhibition of RAGE expression in human monocytes. Methods: We isolated monocytes from: a) 10 type 2 diabetics, and b) 5 age- and sex-matched healthy individuals. CD36 expression and ROS production were evaluated before and after RAGE knockdown. Results: After incubation of monocytes with AGE + bovine serum albumin (BSA), CD36 expression and intracellular ROS increased significantly in all groups. In RAGE-knockdown monocytes, AGE-induced CD36 expression and ROS generation were also significantly inhibited. Conclusions: Blocking RAGE expression using siRNA in human monocytes led to a significant inhibition of CD36 expression and ROS production, suggesting a positive interaction between RAGE, CD36 expression and ROS generation in monocytes.

The C‐terminal Region of HPNAP Activates Neutrophils and Promotes Their Adhesion to Endothelial Cells

Entire Helicobacter Pylori Neutrophil Activated Protein (HPNAP) and its truncated forms NH2‐terminal region HPNAP1–57 and C‐terminal region HPNAP58–144 after cloning into pET29c vector, purification and removal of LPS traces were subjected to human neutrophil activation. Our results revealed that the C‐terminal region of HPNAP is indispensable for human neutrophil stimulation and their further adhesion to endothelial cells – a step necessary to H. pylori inflammation – in a ratio equal to that exhibited by the entire protein.

Oral Calcium Supplementation Ambulatory Blood Pressure and Relation to Changes in Intracellular Ions and Sodium-Hydrogen Exchange

BACKGROUND Calcium (Ca2+) supplementation has been shown paradoxically to reduce intracellular Ca2+ and induce vascular relaxation. The aim of the study was to assess 24-h blood pressure (BP) change after Ca2+ supplementation and to investigate its relation to changes in intracellular ions and the activity of the first isoform of sodium-hydrogen exchange (NHE-1) in subjects with hypertension and type 2 diabetes. METHODS This parallel, randomized controlled, single-blinded trial, consisted of 31 patients with type 2 diabetes, and hypertension who were allocated to receive 1,500 mg of Ca2+ per day (n = 15) or no treatment (n = 16) for 8 weeks. RESULTS In the Ca2+ group a decrease of 1.7 +/- 2.7 mm Hg (mean +/- SE) P = 0.52 for mean 24-h systolic BP (SBP) and 2.1 +/- 1.5 mm Hg, P = 0.19 for mean 24-h diastolic BP (DBP) was recorded. Whereas in the control group an increase of 1.4 +/- 2.7 mm Hg, P = 0.59 for mean 24-h SBP and 1.2 +/- 2.8 mm Hg, P = 0.83 for mean 24-h DBP was observed. Intraplatelet Ca2+ decreased whereas intraplatelet magnesium (Mg2+) and erythrocyte K+ increased in the intervention group. Change in mean 24-h SBP in the pooled group correlated with both change in intraplatelet Ca2+ (r = 0.49, P < 0.05) and NHE-1 activity (r = 0.6, P < 0.001). The contribution of intraplatelet Ca2+ was attenuated when both parameters were entered in a multivariate regression model. CONCLUSIONS The present study shows a weak, statistically nonsignificant trend towards association of Ca2+ supplementation on 24-h BP in hypertensive subjects with type 2 diabetes. However, our results indicated an interrelation of [Ca2+]i levels and NHE-1 activity on BP in patients with hypertension and type 2 diabetes.