Increased superoxide anion production by platelets in hypercholesterolemic patients.

Objectives: The purpose of this study was to investigate the relationship between hypercholesterolemia and superoxide anion production.

Background: Experimental studies demonstrated that hypercholesterolemia is associated with enhanced cellular superoxide anion (O2-) production. Aim of the study was to assess whether the same phenomenon occurs in humans.

Molecular and functional characterization of pituitary adenylate cyclase-activating polypeptide (PACAP-38)/vasoactive intestinal polypeptide receptors in pancreatic beta-cells and effects of PACAP-38 on components of the insulin secretory system.

It has been previously demonstrated that pituitary adenylate cyclase-activating polypeptide (PACAP) regulates insulin secretion. PACAP exerts its biological action by binding to at least three different receptor subtypes coupled to different signal transduction mechanisms. The signaling pathways underlying the insulinotropic effect of PACAP involve mainly the activation of adenylate cyclase to form cAMP, which directly and indirectly, through increased intracellular Ca2+, stimulates insulin exocytosis.

GLUT2 and glucokinase expression is coordinately regulated by sulfonylurea.

In the present study we examined the effect of sulfonylurea on the expression of the glucose transporter GLUT2 and the glucose phosphorylating enzyme Glucokinase (GK) in betaTC6-F7 cells; furthermore, we studied the modifications induced by sulfonylurea on glucose-responsiveness and -sensitivity. Results demonstrate that sulfonylurea increases GLUT2 and GK mRNA expression after 24 h in a dose-dependent manner. On the contrary, after 48 and 72 h a time-dependent reduction of both GLUT2 and GK mRNA occurs.

Dose-dependent effect of octreotide on insulin secretion after OGTT in obesity.

Objective: The present study aimed at evaluating the acute effect of increasing doses of octreotide (OCT), a long-acting somatostatin analogue, on glucose tolerance and insulin secretion.

Methods: A standard and two other oral glucose tolerance tests 30 min after subcutaneous administration of OCT were performed in randomized order in each subject. Obese subjects received 10, 25, or 50 microg of OCT; control subjects received only 10 and 25 microg.

The effects of pregnancy steroids on adaptation of beta cells to pregnancy involve the pancreatic glucose sensor glucokinase.

Pregnancy is associated with adaptive changes including increased number and size of beta cells and enhanced gap-junctional coupling among beta cells, increased glucose-induced insulin response and decreased glucose stimulation threshold. The role exerted by pregnancy steroids and lactogenic hormones in the development of islets upregulation during pregnancy has been widely investigated. In the present study we studied the possibility that pregnancy steroids induce functional modifications of beta cells involving the expression and function of glucokinase.