Pneumonia management guidelines--why, how, and where to start.
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Humans↗
Biomedical subjects
L T Shuster
Publications and source records attributed to L T Shuster.
Potential incretins.
A greater plasma concentration of insulin after isoglycemic enteral than after parenteral administration of glucose is called the incretin effect. The primary mediator of this effect, gastric inhibitory polypeptide, may not account for the complete manifestation of this phenomenon. We evaluated other gastroenteric polypeptides with respect to a differential response to oral ingestion of glucose and intravenous administration of glucose at rates that achieved arterial plasma glucose concentrations matched to those from orally administered glucose. Gastrin, peptide histidine methionine, peptide YY, and neurotensin showed increases in plasma concentrations in response to oral ingestion of glucose but not to intravenous administration of glucose. Vasoactive intestinal polypeptide showed no increased concentration in response to either oral or intravenous administration of glucose. The differential responses to orally and intravenously administered glucose noted in the former gastroenteric polypeptides qualifies them as potential mediators of the incretin effect.
Administration, Oral↗
Incretin effect due to increased secretion and decreased clearance of insulin in normal humans.
To assess the contribution of changes in insulin secretion and clearance to the incretin effect (greater insulinemia after oral than after intravenous glucose), 10 healthy subjects were studied after oral glucose (1 g/kg body wt) and again when glucose was infused intravenously at rates to match arterialized plasma glucose concentrations after oral glucose. Although basal and integrated plasma glucose did not differ between oral and intravenous glucose, integrated responses of insulin (3.3 +/- 0.5 vs. 1.8 +/- 0.4 mU ml-1.240 min-1, P less than .001), C-peptide (456.5 +/- 58.5 vs. 327.9 +/- 46.3 ng.ml-1.240 min-1, P = .002), gastric inhibitory polypeptide, (16.8 +/- 3.5 vs. -2.8 +/- 1.0 micrograms.ml-1.240 min-1, P less than .001), and insulin secretion (6.6 +/- 1.1 vs. 4.7 +/- 0.7 U.240 min-1, P = .003) were greater with oral than intravenous glucose. However, insulin clearance, whether calculated as the molar ratio of integrated C-peptide to integrated insulin responses (6.9 +/- 0.7 vs. 14.2 +/- 3.8, P = .005) or from the formula insulin clearance equals insulin secretion divided by integrated insulin responses (1.1 +/- 0.2 vs. 2.5 +/- 0.7 L.min-1.m-2, respectively, P = .002), was less for oral than for intravenous glucose. Therefore, the incretin effect is mediated both by increased secretion and decreased clearance of insulin.
Administration, Oral↗