Development of sensitive immunoassays to detect amylin and amylin-like peptides in unextracted plasma

Exenatide (exendin-4) is an incretin mimetic with potential antidiabetic activity. This study examined the effects of a continuous subcutaneous (SC) infusion of exenatide (0.2, 0.4, 0.6, or 0.8 microg/kg/day) or placebo (PBO) on glycemic control over 23 h intervals. Twelve subjects with type 2 diabetes treated with metformin and/or diet received 10 infusions (4 exenatide, 6 PBO) on consecutive days. Exenatide was given in a dose-increasing design with at least one placebo infusion between each exenatide infusion, and with meals and a snack provided during the first 14 h of infusion. Plasma exenatide concentrations were dose-proportional. Plasma glucose (4-23 h) was lower in all exenatide arms compared to placebo (p<0.0001). The change in insulin/glucagon ratio and amylin concentrations from pre-infusion to post-infusion was increased (p<0.005, p<0.05, respectively) in the combined exenatide arms, but remained unchanged in the placebo groups. Nausea and vomiting were the most common treatment emergent adverse events. Exenatide infusion also appeared to have positive effects on beta-cell and alpha-cell function as measured by proinsulin/insulin ratios and mean glucagon concentrations. In summary, exenatide lowered plasma glucose during both prandial and fasting states when delivered as a continuous SC infusion over twenty-three hours, suggesting that exenatide can provide day-long glycemic control in patients with type 2 diabetes.

Section: Assaysmentioning

confidence: 99%

Day-long Subcutaneous Infusion of Exenatide Lowers Glycemia in Patients with Type 2 Diabetes

Taylor¹,

Kim²,

Nielsen³

et al. 2005

“…Glycosylated amylin are represented by larger molecules containing o-linked oligosaccharides near the Nterminus of the molecule (17). Previous reports have indicated that total amylin is more elevated compared to non-glycosylated amylin in impaired glucose tolerance, early NIDDM and gestational diabetes (16,18,19).…”

Section: Introductionmentioning

confidence: 94%

“…We have recently developed two assays for the detection of amylin immunoreactivity in human plasma (16). One assay is specific for non-glycosylated amylin, while the other measures total amylin immunoreactivity (non-glycosylated and glycosylated amylin).…”

Section: Introductionmentioning

confidence: 99%

Plasma Amylin Immunoreactivity and Insulin Resistance in Insulin Resistant Relatives of Patients with Non-Insulin-Dependent Diabetes Mellitus

Nyholm

Ms²,

Je³

et al. 1998

To explore the potential relationship between concentrations of circulating amylin and the insulin resistance observed in first-degree relatives of patients with non-insulin-dependent-diabetes mellitus (NIDDM), we studied 40 relatives compared to 35 matched controls. Two newly developed immunoassays that measure either non-glycosylated or total amylin were applied. All subjects were examined by an oral glucose tolerance test (OGTT) and by a hyperinsulinemic euglycemic clamp (insulin infusion: 0.6 mU/kg/min). Glucose tolerance was normal in all, but insulin-stimulated glucose uptake (Rd) was diminished in the relatives (p < 0.001). Area under the curves (AUCs) during OGTT for plasma glucose (p < 0.01) and serum insulin (p=0.08), but not for plasma total and non-glycosylated amylin, were higher in relatives versus controls. In both groups, inverse correlations were found between Rd and AUC for plasma total and non-glycosylated amylin (p [all]<0.05). However, in multiple linear regression analyses, plasma total and non-glycosylated amylin failed to influence Rd independent of serum insulin and family history-of NIDDM. In conclusion, this study demonstrated inverse correlations between Rd and circulating concentrations of plasma total and non-glycosylated amylin in relatives and matched controls. These data, however, do not support the hypothesis that physiological amylin concentration are a major importance for the insulin resistance in relatives of NIDDM patients.

“…Plasma amylin and pramlintide concentrations were measured with an immunoenzymetric assay as previously described (12), using a rat arnylin standard in a plasma mimic (24). Plasma glucose and lactate were determined by glucose oxidase and lactate oxidase methods, respectively, on a YSI 2300-STAT (YSI, Yellow Springs, OH).…”

Section: Analysesmentioning

confidence: 99%

Nephrectomy Decreases Amylin and Pramlintide Clearance in Rats

Vine¹,

Smith²,

R³

et al. 1998

Amylin is a 37 amino acid hormone, co-secreted with insulin from the pancreatic beta-cell in response to nutrient stimuli. Because the human amylin analog, pramlintide, is being tested in patients with diabetes mellitus, a known risk factor for nephropathy, we examined the role of the kidney on amylin and pramlintide metabolism and action in functionally nephrectomized rats. Nephrectomy markedly altered amylin metabolism: it increased incremental area under the plasma amylin concentration curve 3.6-fold (P<0.001) and increased the elimination half-life from 17+/-1 to 26+/-2 minutes (P < 0.01) after subcutaneous injection of 100 microg amylin. Nephrectomy decreased plasma amylin clearance from 20.3+/-1.1 to 7.9+/-0.4 mL/min (P < 0.0001). Thus, at these doses in the rat, the kidney is important for metabolizing amylin and pramlintide.