Infantile Pyknocytosis in a Premature Dichorionic Diamniotic Twin.

Infantile pyknocytosis is a rare and self-limiting cause of hemolytic anemia in neonates. It can result in severe anemia and hyperbilirubinemia. The pathogenesis is unknown: a genetic origin has been discussed; however, based on the current literature it is not clear which genetic mutations should be considered. We present a case of a premature twin, in whom genetic screening was performed. Genetic mutations in 46 genes associated with hereditary hemolytic anemia and dyserythropoietic anemia were tested. No mutations were found. In infantile pyknocytosis, a genetic defect in these genes is unlikely.

An explorative study of in vivo digestive starch characteristics and postprandial glucose kinetics of wholemeal wheat bread.

BACKGROUND: Based on in vitro measurements, it is assumed that starch in wholemeal bread is rapidly digestible, which is considered to be less desirable for health. AIM OF THE STUDY: To evaluate the in vitro prediction, we characterized starch digestion of wholemeal wheat bread (WB) and postprandial glucose kinetics in healthy volunteers. METHODS: In a crossover study 4 healthy men ingested either intrinsically (13)C-enriched WB (133 g) or glucose (55 g) in water. Plasma glucose and insulin concentrations were monitored during 6 h postprandially. Using a primed continuous infusion of D-[6,6-(2)H(2)] glucose, the rate of systemic appearance of glucose was estimated (reflecting glucose influx) and the endogenous glucose production calculated. RESULTS: The glucose influx rate after WB was comparable with that after glucose in the early postprandial phase (0-2 h) (P = 0.396) and higher in the late postprandial phase (2-4 h) (P = 0.005). Despite the same initial glucose influx rate the 0-2 h incremental area under the curve (IAUC) of insulin after WB was 41% lower than after glucose (P = 0.037). Paradoxically endogenous glucose production after WB was significantly more suppressed than after glucose (0-2 h IAUC: P = 0.015, 2-4 h IAUC: P = 0.018). CONCLUSIONS: Starch in WB seems to be partly rapidly and partly slowly digestible. Postprandial insulin response and endogenous glucose production after WB ingestion might not solely be determined by the digestive characteristics of starch; other components of WB seem to affect glucose homeostasis. In vitro measurements might not always predict in vivo starch digestion precisely.

The rate of intestinal glucose absorption is correlated with plasma glucose-dependent insulinotropic polypeptide concentrations in healthy men.

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) both play a role in the control of glucose homeostasis, and GIP is implicated in the regulation of energy storage. The capacity of carbohydrates to induce secretion of these incretin hormones could be one of the factors determining the metabolic quality of different types of carbohydrates. We analyzed the correlation between the rate of intestinal absorption of (starch-derived) glucose and plasma concentrations of GLP-1 and GIP after ingestion of glucose and starchy foods with a different content of rapidly and slowly available glucose. In a crossover study, glucose, insulin, GLP-1, and GIP concentrations were monitored for 6 h after consumption of glucose, uncooked cornstarch (UCCS) or corn pasta in 7 healthy men. All test meals were naturally labeled with 13C. Using a primed, continuous D-[6,6-2H2]glucose infusion, the rate of appearance of exogenous glucose (RaEx) was estimated, reflecting the rate of intestinal glucose absorption. GLP-1 concentrations increased significantly from 180 to 300 min after ingestion of UCCS, the starch product with a high content of slowly available glucose. A high GIP response in the early postprandial phase (15-90 min) occurred after consumption of glucose. There was a strong positive within-subject correlation between RaEx and GIP concentrations (r = 0.73, P < 0.01) across the test meals. Rapidly and slowly digestible carbohydrates differ considerably in their ability to stimulate secretion of incretin hormones; the metabolic consequences of such differences warrant exploration.

Hydroxycitric acid delays intestinal glucose absorption in rats.

In this study, we investigated in rats if hydroxycitric acid (HCA) reduces the postprandial glucose response by affecting gastric emptying or intestinal glucose absorption. We compared the effect of regulator HCA (310 mg/kg) and vehicle (control) on the glucose response after an intragastric or intraduodenal glucose load to investigate the role of altered gastric emptying. Steele's one-compartment model was used to investigate the effect of HCA on systemic glucose appearance after an intraduodenal glucose load, using [U-(13)C]-labeled glucose and d-[6,6-(2)H(2)]-labeled glucose. Because an effect on postabsorptive glucose clearance could not be excluded, the effect of HCA on the appearance of enterally administered glucose in small intestinal tissue, liver, and portal and systemic circulation was determined by [U-(14)C]glucose infusion. Data show that HCA treatment delays the intestinal absorption of enterally administered glucose at the level of the small intestinal mucosa in rats. HCA strongly attenuated postprandial blood glucose levels after both intragastric (P < 0.01) and intraduodenal (P < 0.001) glucose administration, excluding a major effect of HCA on gastric emptying. HCA delayed the systemic appearance of exogenous glucose but did not affect the total fraction of glucose absorbed over the study period of 150 min. HCA treatment decreased concentrations of [U-(14)C]glucose in small intestinal tissue at 15 min after [U-(14)C]glucose administration (P < 0.05), in accordance with the concept that HCA delays the enteral absorption of glucose. These data support a possible role for HCA as food supplement in lowering postprandial glucose profiles.