Report prepared by C.J. Greenbaum 1, T. J. Wilkin 2 and J. P. Palmer 1 on behalf of the Immunology and Diabetes Workshops and participating laboratories*
An increase in plasma beta-endorphin concentrations during exercise has been reported in adult men and women by several investigators. However, very little is known about this physiological hormonal response to exercise in children. In this study, we investigated plasma beta-endorphin, ACTH and GH responses to exercise in 40 prepubertal and pubertal children. Subjects were recruited as part of a population of children and adolescents presenting growth retardation and were selected on the basis of the absence of any clinical or biological signs of endocrine or metabolic disease. There were 16 girls and 24 boys with 24 prepubertal and 16 pubertal individuals. A standardised 15 min workload on cycloergometer was used to progressively increase the heart rate of the children up to 90% of the theoretical maximal value. Exercise resulted in a significant increase (p < 0.01) in plasma beta-endorphin (mean +/- SEM) (4.26 +/- 0.47 vs 5.74 +/- 0.56 fmol/ml), ACTH (3.71 +/- 0.41 vs 6.2 +/- 0.62 fmol/ml) and GH (147 +/- 29 vs 364 +/- 67 fmol/ml). The percentage of children with significant hormonal response to exercise was about 75% for each of the 3 hormones but only 3 of the 40 children studied did not show any hormonal response to exercise. Exercise-induced increases in plasma beta-endorphin and ACTH were significantly correlated (p < 0.01). By contrast, there was no significant relationship between GH and beta-endorphin or ACTH values. Furthermore, whereas exercise-induced plasma GH increase was significantly higher in pubertal than in prepubertal children (p < 0.001), corresponding beta-endorphin and ACTH levels were quite similar in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Glucose clamp experiments have shown that patients with reactive postprandial hypoglycaemia (PRH) frequently have an increased glucose disposal, but the relative involvement of insulin sensitivity (SI) and glucose effectiveness (Sg) in this process remains unknown. The minimal model approach was used to compare 13 patients in whom moderate reactive hypoglycaemia ( < 3.3 mmol) had been previously diagnosed and 13 matched controls. The intravenous glucose tolerance test (IVGTT, 0.5 g/kg glucose IV) with 0.02 U/kg insulin given at the 19th min and frequent sampling over 180 min shows that PRH patients exhibit a higher glucose tolerance coefficient Kg (2.99 +/- 0.26 vs 2.19 +/- 0.12; P < 0.02), higher SI [22.9 +/- 6.4 vs 7.18 +/- 0.14 min-1/(microU/ml). 10(-4); P < 0.01] and higher Sg (3.84 +/- 0.35 vs 2.92 +/- 0.79 min-1. 10(-2); P < 0.05). The increase in Sg is explained by an increase in its component basal insulin effectiveness (BIE: 1.2 +/- 0.27 min-1.10(-2) in PRH subjects vs 0.58 +/- 0.07; P < 0.05) rather than an increase in Sg at zero insulin. The increase in BIE results from the high values of SI. In 4 PRH subjects SI and Sg were within the normal range, and the increase in Kg evidenced in the 9 others was explained by an increase in SI alone in 3 cases, in Sg alone in 1 case, and both SI and Sg in 5 cases. Thus, in sedentary subjects, the previously reported rise in tissue glucose assimilation is mainly explained by an increased insulin-mediated glucose disposal rather than non-insulin-mediated glucose disposal.
The oral glucose tolerance test is not specific for diagnosing postprandial reactive hypoglycaemia, since it too frequently induces low blood glucose values in subjects who have never complained of symptoms of this. By contrast, the mixed meal tests are deceptive for this purpose because they do not induce hypoglycaemia in subjects who have complained of of hypoglycaemic symptoms. We investigated the frequency of hypoglycaemia after a standardized hyperglucidic breakfast test in three groups of subjects:group A, 43 control subjects; group B, 38 postprandial reactive hypoglycaemic patients; group C, 1193 asymptomatic subjects undergoing assessment of glycoregulation. In the 38 subjects with suspected reactive hypoglycaemia the mean blood glucose nadir was 3.48 +/- 0.08 mmol/l, i.e. lower than in control subjects (4.83 +/- 0.13 p < 0.0001). Blood glucose levels less than 3.3 mmol/l were found in 47.3% of subjects with suspected postprandial reactive hypoglycaemia (group B), i.e more frequently than in control subjects (group A: 2.2% p = 1.6 x 10(-6)) and asymptomatic subjects (group C: 1% p = 8 x 10(-22)). This markedly higher frequency of low blood glucose values in subjects with postprandial symptoms compared with control and asymptomatic subjects suggests that this test detects a tendency to hypoglycaemia after a standardized hyperglucidic breakfast. Since this test mimics average French eating habits, the results suggest that the patients undergo such symptoms in their everyday life, and that the hyperglucidic breakfast test is a simple alternative to ambulatory glucose sampling for diagnosis of postprandial reactive hypoglycaemia.
Seven simple strategies (including transport containers with an effective temperature analyser and audits) decreased blood wastage, especially in the ICU and operating theatre.
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