Proapelin is processed extracellularly in a cell line-dependent manner with clear modulation by proprotein convertases.

Apelin is a peptide hormone that binds to a class A GPCR (the apelin receptor/APJ) to regulate various bodily systems. Upon signal peptide removal, the resulting 55-residue isoform, proapelin/apelin-55, can be further processed to 36-, 17-, or 13-residue isoforms with length-dependent pharmacological properties. Processing was initially proposed to occur intracellularly. However, detection of apelin-55 in extracellular fluids indicates that extracellular processing may also occur. To test for this, apelin-55 was applied exogenously to HEK293A cells overexpressing proprotein convertase subtilisin kexin 3 (PCSK3), the only apelin processing enzyme identified thus far, and to differentiated 3T3-L1 adipocytes, which endogenously express apelin, PCSK3 and other proprotein convertases. Analysis of culture media constituents from each cell type by high performance liquid chromatography-mass spectrometry and western blot demonstrated a time-dependent decrease in apelin-55 levels. This decrease was partially, but not fully, attenuated by PCSK inhibitor treatment in both cell lines. Comparison of the resulting apelin-55-derived peptide profile between the two cell lines demonstrated distinct processing patterns, with apelin-36 production apparent in 3T3-L1 adipocytes vs. detection of the prodomain of a shorter isoform (likely the apelin-13 prodomain, observed after additional proteolytic processing) in PCSK3-transfected HEK293A cells. Extracellular processing of apelin, with distinct cell type dependence, provides an alternative mechanism to regulate isoform-mediated physiological effects of apelin.

Insulin Pump Use and Diabetic Ketoacidosis Risk in Type 1 Diabetes: Secular Trends over Four Decades.

Introduction: Continuous subcutaneous insulin infusion (CSII) in type 1 diabetes has been regarded as a major diabetic ketoacidosis (DKA) risk factor. We aimed to determine secular trends in risk since CSII implementation in the 1980s. Research Design and Methods: We assessed the relationship between time-varying CSII use and DKA events from 1983 to 2017 and by each decade in the 1441 Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study participants using crude and adjusted Cox proportional hazards models. Results: Time-varying CSII exposure was associated with significantly higher DKA risk in the 1980s (adjusted hazard ratio [HR] 5.81; 95% confidence interval [CI] 3.28-10.29; P < 0.001), but in the 2010s, this risk was not significantly elevated (adjusted HR 1.24; 95% CI 0.73-2.12; P = 0.43). Conclusions: DKA risk associated with CSII in type 1 diabetes has declined substantially since the 1980s such that the remaining risk in the past decade appears to be of low magnitude.

A Glucagonoma Presenting as Cerebral Vein Thrombosis and Diabetes.

Glucagonomas are rare pancreatic neuroendocrine tumors (pNETs), malignant in 80% of cases, thus highlighting the importance of early diagnosis and treatment. Primary manifestations are diabetes, dermatosis, depression, weight loss, and deep vein thrombosis. Unlike other pNETs, glucagonomas are associated with a higher incidence of thromboembolic events, often resulting in death. We present the case of a glucagonoma patient whose primary manifestation was cerebral sinus venous thrombosis (CS-VT). Early diagnosis enabled curative resection. The purpose of this paper is to review the underlying mechanisms associated with increased coagulopathy in glucagonomas.

The role of ghrelin in the regulation of glucose homeostasis.

Ghrelin is a 28-amino acid (aa) stomach-derived peptide discovered in 1999 as the endogenous ligand for growth hormone secretagogue-receptor (GHS-R). Ghrelin-producing cells constitute a distinct group of endocrine cells dispersed throughout the gastric mucosa and to a lesser extent in the small intestine and the endocrine pancreas. Ghrelin plasma levels rise during fasting and chronic caloric restriction to stimulate food intake and fat storage and to prevent life-threatening falls in blood glucose. Plasma ghrelin levels decrease after a meal is consumed and in conditions of energy surplus (such as obesity). Ghrelin has emerged as a key player in the regulation of appetite and energy homeostasis. Ghrelin achieves these functions through binding the ghrelin receptor GHS-R in appetite-regulating neurons and in peripheral metabolic organs including the endocrine pancreas. Ghrelin levels are negatively correlated with body mass index (BMI) and insulin resistance. In addition, ghrelin secretion is impaired in obesity and insulin resistance. Several studies highlight an important role for ghrelin in glucose homeostasis. Genetic, immunological, and pharmacological blockade of ghrelin signaling resulted in improved glucose tolerance and insulin sensitivity. Furthermore, exogenous ghrelin administration was shown to decrease glucose-induced insulin release and increase glucose level in both humans and rodents. GHS-R was shown to be expressed in pancreatic ß-cells and ghrelin suppressed insulin release via a Ca2+-mediated pathway. In this review, we provide a detailed summary of recent advances in the field that focuses on the role of insulin and insulin resistance in the regulation of ghrelin secretion and on the role of ghrelin in glucose-stimulated insulin secretion (GSIS).

Diabetic foot complications and their risk factors from a large retrospective cohort study.

BACKGROUND: Foot complications are considered to be a serious consequence of diabetes mellitus, posing a major medical and economical threat. Identifying the extent of this problem and its risk factors will enable health providers to set up better prevention programs. Saudi National Diabetes Registry (SNDR), being a large database source, would be the best tool to evaluate this problem. METHODS: This is a cross-sectional study of a cohort of 62,681 patients aged ≥ 25 years from SNDR database, selected for studying foot complications associated with diabetes and related risk factors. RESULTS: The overall prevalence of diabetic foot complications was 3.3% with 95% confidence interval (95% CI) of (3.16%-3.44%), whilst the prevalences of foot ulcer, gangrene, and amputations were 2.05% (1.94%-2.16%), 0.19% (0.16%-0.22%), and 1.06% (0.98%-1.14%), respectively. The prevalence of foot complications increased with age and diabetes duration predominantly amongst the male patients. Diabetic foot is more commonly seen among type 2 patients, although it is more prevalent among type 1 diabetic patients. The Univariate analysis showed Charcot joints, peripheral vascular disease (PVD), neuropathy, diabetes duration ≥ 10 years, insulin use, retinopathy, nephropathy, age ≥ 45 years, cerebral vascular disease (CVD), poor glycemic control, coronary artery disease (CAD), male gender, smoking, and hypertension to be significant risk factors with odds ratio and 95% CI at 42.53 (18.16-99.62), 14.47 (8.99-23.31), 12.06 (10.54-13.80), 7.22 (6.10-8.55), 4.69 (4.28-5.14), 4.45 (4.05-4.89), 2.88 (2.43-3.40), 2.81 (2.31-3.43), 2.24 (1.98-2.45), 2.02 (1.84-2.22), 1.54 (1.29-1.83), and 1.51 (1.38-1.65), respectively. CONCLUSIONS: Risk factors for diabetic foot complications are highly prevalent; they have put these complications at a higher rate and warrant primary and secondary prevention programs to minimize morbidity and mortality in addition to economic impact of the complications. Other measurements, such as decompression of lower extremity nerves, should be considered among diabetic patients.