CONTEXT Polycystic ovary syndrome (PCOS) is frequently associated with insulin resistance. OBJECTIVE The aim of the study was to investigate a putative role of the adipokines retinol-binding protein 4 (RBP4), adiponectin, and visfatin in a cohort of patients with PCOS and their response to treatment with pioglitazone. DESIGN AND SETTING We conducted a randomized, controlled, double-blind st...

Recent studies have suggested that retinol binding protein 4 (RBP4), an adipocytokine related to insulin resistance (IR), may play an important role in the development of atherosclerosis and cardiovascular diseases (CVD). Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) is one of the most common causes of atherosclerosis. Hyperinsulinism promotes proliferation of VSM...

Vitamin A refers to a spectrum of retinoid compounds (retinol, retinoic acid, and retinaldehyde) with important functions in different tissues, including the retina and skin. Retinoids regulate metabolic pathways through binding to two nuclear hormone receptors: retinoic acid receptor and retinoid X receptor. In humans, approximately 80% of the body reservoir of vitamin A is stored in the liver...

Circulating transthyretin (TTR) is a critical determinant of plasma retinol-binding protein 4 (RBP4) levels. Elevated RBP4 levels cause insulin resistance, and the lowering of RBP4 levels improves glucose homeostasis. Since lowering TTR levels increases renal clearance of RBP4, we determined whether decreasing TTR levels with antisense oligonucleotides (ASOs) improves glucose metabolism and ins...

BACKGROUND The relative dose response (RDR) test, which quantifies the increase in serum retinol after vitamin A administration, is a qualitative measure of liver vitamin A stores. Particularly in preterm infants, the feasibility of the RDR test involving blood is critically dependent on small sample volumes. OBJECTIVES This study aimed to assess whether the RDR calculated with retinol-bindin...

CONTEXT Exercise training enhances insulin sensitivity. Changes in retinol-binding protein-4 (RBP4) and adiponectin levels are linked to insulin resistance. OBJECTIVE We tested whether the insulin-sensitizing effect of exercise is associated with age-related changes in circulating RBP4 and adiponectin levels in women. DESIGN, SUBJECTS, AND INTERVENTION We studied 36 healthy young (22.4 +/- ...

Background & Objective: Diabetic retinopathy (DR) is a common microvascular complication of type 2 diabetes mellitus (T2DM) and the leading cause of vision loss in working-age adults. Vitamin A (retinol) has a role in the mechanism of vision process and retinol binding protein-4 (RBP4), is a carrier of vitamin A, and as an adipokine may be associated with increased risk for insulin resistance a...

OBJECTIVE Retinol-binding protein 4 (RBP4) has recently been reported to be associated with insulin resistance (IR) and the metabolic syndrome by a number of researchers in various populations. However, controversies are present among different studies, which might be due to the differences between various ethnic, age, and sex groups. This study aimed to determine whether RBP4 can be assumed as...

BACKGROUND Retinol-binding protein-4 (RBP4) is a novel adipokine able to modulate the action of insulin in several tissues. A variable degree of insulin resistance characterizes the vast majority of hypertensive (HYP) patients. The aim of this study was to evaluate the relationship between RBP4 and essential hypertension, exploring potential links between RBP4 and other adipokines with some pro...

OBJECTIVE Adipokines have been implicated in metabolic regulation and the immune response thus providing a molecular mechanism for the interaction between these two systems. Retinol binding protein 4 (RBP4) is a novel adipokine that plays a role in the pathophysiology of obesity-induced insulin resistance, as well as in the modulation of inflammation. The aim of this study was to determine whet...