L. Cominacini

Oxidized low-density lipoprotein increases the production of intracellular reactive oxygen species in endothelial cells : inhibitory effect of lacidipine

Objective The mechanisms by which oxidized low-density lipoprotein (ox-LDL) induces the expression of adhesion molecules on endothelial cells (HUVECs) are still not clear. The signal transduction pathways for these binding molecules include the translocation of the transcription factor NF-kB and the intracellular reactive oxygen species (ROS) are said to play a key role in this process. Aim of this study was (1) to evaluate the effect of ox-LDL on intracellular production of ROS in culture of HUVECs; (2) to evaluate if the intracellular increase of ROS induced by ox-LDL is mediated by the binding to a specific endothelial receptor; (3) to ascertain if lacidipine can decrease ox-LDL-induced ROS production in HUVECs. Methods Five *MCu2 + ox-LDL were incubated with HUVECs for 5 min. 2′,7′-Dichlorofluorescein (DCF) as an expression of intracellular ROS production, was measured by flow cytometry. Results ox-LDL induced a significant dose-dependent increase in DCF production (P < 0.001) through the binding to a specific receptor. The preincubation of HUVECs with radical scavengers compounds and lacidipine significantly reduced (P < 0.001) the ox-LDL-induced DCF production. Conclusions ox-LDL increased the intracellular formation of ROS through the ligation to a specific endothelial receptor. Preincubation of HUVECs with lacidipine, a calcium antagonist with antioxidant properties, significantly reduced the intracellular ROS formation induced by ox-LDL. We propose that the effect of lacidipine on adhesion molecule expression and on NF-kB activation can be explained by its effect on intracellular ROS formation.

Lacidipine inhibits the activation of the transcription factor NF-kappa B and the expression of adhesion molecules induced by pro-oxidant signals on endothelial cells

Objective The adhesion of monocytes to endothelium, an early event in atherosclerosis is mediated by cell adhesion molecules. Signal-transduction pathways for these binding molecules include the translocation of the transcription factor NF-κB; moreover, intracellularly generated oxygen-derived free radicals play a major role in this process. In this study we evaluated the extent to which lacidipine, a calcium antagonist with antioxidant properties, affects the expression of intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin on human umbilical vein endothelial cells, induced by different pro-oxidant signals such as oxidized low density lipoprotein (LDL) and tumor necrosis factor-α (TNF-α). Methods We incubated 5 mmol/l Cu2+-oxidized LDL and TNF-α (2 ng/ml) with human umbilical vein endothelial cells for 48 and 6 h, respectively. ICAM-1, VCAM-1 and E-selectin were measured by flow cytometry. NF-κB was evaluated by electrophoretic mobility shift assay. Results The incubation of 5 μmol/l Cu2+-oxidized LDL not only caused a dose-dependent increase in ICAM-1, VCAM-1 and E-selectin (P <0.001), but also synergically increased their TNF-α–induced expression (P <0.001). The addition of lacidipine to human umbilical vein endothelial cells significantly reduced the expression of ICAM-1, VCAM-1 and E-selectin induced by TNF-α alone or with oxidized LDL (P <0.001). The reduction in adhesion molecule expression caused by lacidipine was paralleled by a significant fall in NF-κB translocation. Conclusions The results suggest that lacidipine may have prevented NF-κB-mediated adhesion molecule expression by exerting its effects on oxygen-derived free radicals. The results support previous observations that lacidipine may have therapeutic effects in atherosclerosis.

Adiponectin gene expression and adipocyte NF-κB transcriptional activity in elderly overweight and obese women : inter-relationships with fat distribution, hs-CRP, leptin and insulin resistance

Objective:The regulatory processes that modulate adiponectin production and the mechanisms involved in nuclear factor kB (NF-kB) transcriptional activity in human adipocytes are not yet fully known. The aim of our study was to evaluate the inter-relationships between body fat, fat distribution, systemic inflammation, insulin resistance, leptin and the serum and subcutaneous adipose tissue gene expression levels of tumor necrosis factor-alpha (TNF-α), adiponectin and the inhibitor kappa B-alpha (IkB-α), in subjects with a wide range of body mass index (BMI). We also wanted to determine which of these variables was most closely related to adiponectin gene expression and adipocyte NF-kB transcriptional power.Methods:A total of 27 women aged between 50 and 80 years, with BMI ranging from 22.1 to 53.3 kg/m2, were studied. In all subjects BMI, waist circumference, body composition by dual X-ray absorptometry, triglycerides, cholesterol, high-density lipoprotein cholesterol (HDL-Ch), glucose, insulin, homeostasis model assessment of insulin resistance (HOMA), high-sensitive C-reactive protein (hs-CRP), serum adiponectin, leptin and TNF-α were evaluated. Subcutaneous adipose tissue biopsies were taken from the abdomen of all subjects and the mRNA levels of adiponectin, TNF-α and IkB-α were determined.Results:BMI and waist circumference were associated positively with leptin, HOMA, and hs-CRP, and negatively with HDL-Ch; waist was also associated with adiponectin and IkB-α mRNA. HOMA was negatively associated with serum adiponectin and adiponectin mRNA. Hs-CRP was negatively associated with IkB-α mRNA, and was positively associated with HOMA. Step-down multiple regression analysis was performed to determine the joint effects of BMI, waist circumference, triglycerides, HDL-Ch, HOMA, hs-CRP, leptin, serum and TNF-α mRNA on adiponectin gene expression: waist circumference and leptin were both included in the best fitting regression equation for predicting adiponectin gene expression (R 2=0.403, P=0.006). Stepwise multiple regression analysis was performed, considering IkB-α mRNA as a dependent variable and BMI, waist, HDL-Ch, HOMA, hs-CRP and adiponectin mRNA as independent variables. Adiponectin mRNA was the only variable to enter the regression (R2=0.406, P<0.001).Conclusion:Our results suggest that abdominal adiposity and leptin are independent predictors of adiponectin gene expression and that in human adipocytes, adiponectin gene expression is strongly related to IkB-α mRNA.

Suppressive effect of chronic glucocorticoid treatment on circulating calcitonin in man.

INTRODUCTION Many factors contribute to glucocorticoid-in deced osteopenia.Corticosteroid excess leads to in testinal malabsorption of calcium through a direct inhibition of the intestinal absorptive process(l, 2) or through an impaired vitamin D metabolism (3, 4). A direct action of the corticosteroid on bone tissue has also suggested (5). On the other hand an impaired calcitonin (CT) secretion has been suggested to be a factor in the pathogenesis of some forms of decreased bone mass (6,7) . To explore a possible relationship between CT secretion and steroid induced bone loss we studied the secretion of this hormone before and during long term treatment with eorticosteroids.

Somatostatin inhibition of insulin secretion in insulin-producing tumors.

Abstract Synthetic linear somatostatin infused in two patients with insulin producing tumors lowered slightly basal insulin and a little less basal glucose levels; above all it inhibited insulin release induced by glucose, glucagon, and tolbutamide.

Discriminant analysis in the differential diagnosis of hypercalcaemia.

Linear discriminant analysis, a multivariate statistical procedure, applied to serum calcium, phosphate, alkaline phosphatase, bicarbonate, chloride, creatinine and tubular reabsorption of phosphate, proved to be effective in distinguishing patients with Primary Hyperparathyroidism from other hypercalcaemic patients in eighty‐four retrospective cases. The application of the model to thirty‐four prospective cases enabled us to separate correctly, hyperparathyroid patients from non‐parathyroid hypercalcaemic patients.

Serum thyroid hormone concentrations and weight loss relationships in eight obese women during semistarvation.

Eight obese female patients were studied over a period of 15 days whilst on 300 kcal diet. Serum levels of thyroxine and free thyroxine index were not altered significantly by semistarvation. A TRH test performed before and after the diet showed no appreciable change. Weight loss was initially rapid but later slowed despite good patients compliance. Serum concentrations of T3 and reverse T3 (rT3) early decreased (p<0.01) and increased (p<0.05) respectively, but returned towards control levels even before discontinuation of semistarvation. There was a positive correlation between the percentage decrease in body weight and the percentage increase in serum rT3 (p<0.001), and a negative correlation between decrease in body weight and decrease in serum T3 (p<0.001). Our results do not suggest that the variations in serum triiodothyronines limit the weight loss; it is probable, on the contrary, that the weight loss promotes the observed variations in thyroid hormones by as yet unknown adaptive metabolic forces.

Calcium and parathyroid hormone behaviour after exogenous secretin infusion in man.

The response of serum calcium, PTH, CT and gastrin to an infusion of secretin (3 CU/kg/h) over a period of 90 min was studied in ten healthy males and two female patients with hypoparathyroidism.

Effect of Graded Doses of Secretin on Parathormone Serum Levels in Man

5 healthy volunteers were submitted to i.v. infusion for 45 min of graded doses of commercial GIH secretin (0.01, 0.025, 0.05, 0.5, 1 and 2 CU/kg h-1). Parathormone serum levels were measured before and during the infusion. All the dosages of exogenous secretin were followed by a significant increase in serum PTH levels in a dose-dependent fashion. Commercial GIH secretin, even at low doses, seems to increase circulating parathyroid hormone levels significantly.

FAILURE OF SOMATOSTATIN TO DIAGNOSE ORGANIC HYPERINSULINISM

SUMMARY. In four patients with organic hyperinsulinism (two with surgically proven β‐cell adenomas of the body of the pancreas) a standard tolbutamide test during continuous somatostatin infusion (5 μg/min) was carried out. Tolbutamide‐induced insulin release was completely inhibited by somatostatin as in normal subjects. These results suggest that the inhibition test with somatostatin does not seem to be a better or safer way of diagnosing insulin producing tumours.