Type 1 diabetes is not associated with an increased prevalence of hepatic steatosis

AIM

Non-alcoholic fatty liver disease (NAFLD) is commonly associated with Type 2 diabetes. Recently, it has been suggested that NAFLD is also frequently associated with Type 1 diabetes and diabetic complications. In this study, we set out to determine whether Type 1 diabetes was associated with liver fat content measured using magnetic resonance imaging.

METHODS

One hundred and twenty-eight patients with Type 1 diabetes, 264 patients with Type 2 diabetes and 67 participants without diabetes were included in this study. Hepatic steatosis was defined as a liver fat content > 5.5%.

RESULTS

People with Type 1 diabetes and controls were similar for age and BMI. Liver fat content was significantly higher in patients with Type 2 diabetes than in patients with Type 1 diabetes and controls. In the control group, nine people (13.4%) had steatosis compared with six (4.7%) patients with Type 1 diabetes (P = 0.04). Among patients with Type 2 diabetes group, 166 (62.8%) had steatosis. In multivariate analysis that included patients with Type 1 diabetes and participants without diabetes, steatosis was associated only with BMI, whereas age, sex, statin therapy and Type 1 diabetes were not. In patients with Type 1 diabetes, there was no correlation between liver fat content and estimated glomerular filtration rate or carotid intima media thickness.

CONCLUSIONS

Our data showed that Type 1 diabetes was not associated with an increased prevalence of steatosis. Moreover, our study provided no specific arguments concerning a link between liver fat content and diabetic complications in patients with Type 1 diabetes.

Purification of Bionanoparticles

The recent demand for nanoparticulate products such as viruses, plasmids, protein nanoparticles, and drug delivery systems have resulted in the requirement for predictable and controllable production processes. Protein nanoparticles are an attractive candidate for gene and molecular therapy due to their relatively easy production and manipulation. These particles combine the advantages of both viral and non‐viral vectors while minimizing the disadvantages. However, their successful application depends on the availability of selective and scalable methodologies for product recovery and purification. Downstream processing of nanoparticles depends on the production process, producer system, culture media and on the structural nature of the assembled nanoparticle, i.e., mainly size, shape and architecture. In this paper, the most common processes currently used for the purification of nanoparticles, are reviewed.

Comparative binding study of rat natriuretic peptide receptor-A

The natriuretic peptide receptor-A (NPR-A) is involved in blood pressure and body fluid regulation in order to help maintain cardiovascular homeostasis. It has been shown that these biological effects are mediated through the natriuretic peptide family of hormones, which bind NPR-A according to the rank order ANP>BNP>>CNP. Previous studies performed with rat kidney papillary tissue suggested the existence of an heterologous NPR-A population since two binding components were obtained for pBNP32, one of high affinity (pK 9.4 +/- 0.1) and the other of lower affinity (pK 7.5 +/- 0.1), while in the same preparation rANP28 binding displayed the expected affinity (pK 10.22 +/- 0.01) and was best fitted with a model involving a single class of binding sites. This apparent heterogeneity of NPR-A in rat kidney papillae could be explained by the presence of two receptor isoforms or of monomeric and oligomeric forms of the same receptor. To investigate the NPR-A binding heterogeneity, we have cloned the rat NPR-A from PC12 cells and compared its pharmacological profile with that of the papillae. Our results with rat NPR-A transfected Cos-P cells show an equivalent pharmacological profile as with the rat tissue, i.e. a high affinity for rANP28 (pK 10.4 +/- 0.1) and two distinctive affinities for pBNP32 (pK 9.74 +/- 0.05 and 7.8 +/- 0.1). Although multiple receptor glycoforms were sometimes detectable by western blotting, only one molecular form was obtained by cross-linking with 125I-rANP28. It thus appears that NPR-A alone can account for the two binding components found in the rat papillae and that a single molecular form of the protein is implicated. We therefore propose that the oligomerization state of the receptors could be responsible for the apparent binding heterogeneity of rat NPR-A.

Characterization of the phosphorylation state of natriuretic peptide receptor-C

Many internalized receptors are known to be phosphorylated within their cytoplasmic domain. Natriuretic peptide receptor-C (NPR-C) is a covalent homodimer primarily involved in the internalization of bound ligand resulting in tissue uptake and degradation of natriuretic peptides. In this report, we have investigated the phosphorylation state of NPR-C receptors present at high level in rat aortic smooth muscle cells (RASM). 32P labeled cells, NPR-C purification and phosphoamino acid analysis clearly demonstrate that NPR-C exists as a phosphoprotein in RASM cells and that phosphorylation occurs exclusively on serine residues. Transient expression of bovine NPR-C in Cos-P cells of kidney origin confirmed that phosphorylation occurs within the cytoplasmic domain of the receptor. These results provide the first evidence for NPR-C phosphorylation as well as a model for future studies of its role in altering receptor function.