Serum Levels of Copeptin are Decreased in Gestational Diabetes Mellitus.

OBJECTIVE: Copeptin, the c-terminal part of pro-Arginine vasopressin, has recently been introduced as a novel risk factor to develop facets of the metabolic syndrome. However, regulation of copeptin in pregnancy-associated metabolic disease, i. e., gestational diabetes mellitus (GDM), has not been fully understood, so far. PATIENTS AND MEASUREMENTS: For this study, 74 GDM patients and 74 healthy, pregnant, age-, body mass index-, and gestational age-matched controls were recruited. Serum levels of copeptin were quantified by an illuminometric assay. Furthermore, copeptin concentrations were correlated to biochemical and anthropometric markers of obesity, glucose and lipid metabolism, renal function, and inflammation. RESULTS: Median [interquartile range] serum copeptin levels were significantly lower in subjects with GDM (3.5 [2.0] pmol/l) as compared to controls (4.4 [3.2] pmol/l) (p<0.05). Furthermore, GDM remained an independent predictor of circulating copeptin in multivariate regression analysis (p<0.05). Moreover, copeptin was independently associated with gestational age at blood sampling (p<0.05). CONCLUSIONS: Copeptin serum levels are significantly lower in GDM as compared to healthy pregnant controls. Further studies are needed to better clarify the pathophysiological role of copeptin in GDM.

Relationship between serum levels of angiopoietin-related growth factor and metabolic risk factors.

Angiopoietin-related growth factor (AGF, also known as angiopoietin-like protein 6) has been introduced as a novel hepatocyte-derived factor, which antagonizes obesity and insulin resistance in mice. However, human studies show conflicting results and are limited to a small cohort of patients. In the current study, we therefore sought to investigate AGF serum levels in a large metabolically well-characterized cohort. AGF serum concentrations were determined by commercial enzyme-linked immunosorbent assay in 697 patients of a cohort from Eastern Germany (Sorbs). Correlations of AGF serum levels with clinical and biochemical measures of glucose and lipid metabolism, as well as markers of renal function, were investigated. In nondiabetic subjects (n=627), AGF was positively correlated with markers of insulin resistance and negatively correlated with high-density lipoprotein cholesterol in univariate analyses (p<0.05). After adjustment for age, gender, and body mass index, none of these factors remained independently associated with AGF, neither in nondiabetic subjects nor in patients with type 2 diabetes mellitus (T2DM) (n=70). However, we confirmed existing data of significantly higher AGF concentrations in patients with T2DM as compared to controls in this large cohort. Circulating AGF is elevated in subjects with T2DM and related to the type of antidiabetic treatment, but is not independently associated with anthropometric parameters, indices of insulin sensitivity and secretion, or a number of other adipokines.

Serum levels of fractalkine are associated with markers of insulin resistance in gestational diabetes.

AIMS: Fractalkine has recently been introduced as an adipokine that improves glucose tolerance. Regulation of fractalkine in gestational diabetes, as well as its association with markers of obesity, glucose and lipid metabolism, inflammation and renal function, has not been elucidated. METHODS: Circulating fractalkine was quantified by enzyme-linked immunosorbent assay in 74 women with gestational diabetes and 74 healthy, pregnant control subjects matched for age, BMI, and gestational age. RESULTS: Median (interquartile range) levels of fractalkine were not significantly different between the two groups [gestational diabetes: 2.24 (2.16) µg/l; control: 2.45 (1.38) µg/l] (P = 0.461). In multivariate linear regression analysis, fractalkine remained independently associated with homeostasis model assessment of insulin resistance (ß = -0.253, P = 0.002) and the proinflammatory adipokine progranulin (ß = 0.218, P = 0.007). CONCLUSIONS: Circulating fractalkine is not different between women with gestational diabetes and control subjects, but the adipokine is independently associated with markers of insulin resistance and proinflammatory progranulin in pregnancy.

Adipocyte fatty acid-binding protein is released from adipocytes by a non-conventional mechanism.

Adipocyte fatty acid-binding protein (AFABP) is an adipokine, which induces insulin resistance. However, AFABP does not possess any secretion-directed signals and the mechanisms for AFABP release have not been thoroughly assessed so far. In the current study, mechanisms for AFABP secretion were elucidated in 3T3-L1 adipocytes in vitro in the presence or absence of hormonal stimulation, calcium ionophore and secretion inhibitors by cell fractionation experiments, immunoblotting and ELISAs. We demonstrate that AFABP secretion is upregulated during adipocyte differentiation. AFABP secretion is not influenced by treatment with protein secretion inhibitors that block vesicular traffic at the endoplasmic reticulum and the Golgi apparatus. AFABP is secreted partially by adipocyte-derived microvesicles (ADMs), an established mechanism for unconventional secretion from adipocytes. Both total and ADM-secreted AFABP are downregulated by insulin and upregulated by the calcium ionophore ionomycin. Furthermore, murine RAW 264.7 macrophages secrete AFABP and AFABP release from these cells is upregulated by lipopolysaccharide treatment. Taken together, these results suggest that AFABP is actively released by unconventional mechanisms and by ADMs from 3T3-L1 adipocytes. Furthermore, AFABP secretion from fat cells is regulated by insulin and intracellular calcium.

A novel GNAS1 mutation in a German family with Albright's hereditary osteodystrophy.

Albright's hereditary osteodystrophy (AHO) is an inherited disorder and results from heterozygous loss of function mutation within the human G (s)α gene (GNAS1). AHO appears in two phenotypes, that may occur within the same family. Pseudohypoparathyroidism type Ia (PHP Ia) comprises the clinical features of AHO associated with parathyroid hormone (PTH) resistance while pseudo-pseudohypoparathyroidism (PPHP) includes AHO features without PTH resistance. In the present study we report a mother and a daughter with PPHP and PHP Ia respectively. The 13 exons of GNAS1 were analysed by PCR and direct sequencing. We identified a heterozygous missense mutation in exon 1. This novel mutation results in a stop at codon 35 and a truncated non-functional GNAS1 protein.