Chronic exposure to elevated norepinephrine suppresses insulin secretion in fetal sheep with placental insufficiency and intrauterine growth restriction.

In this study, we examined chronic norepinephrine suppression of insulin secretion in sheep fetuses with placental insufficiency-induced intrauterine growth restriction (IUGR). Glucose-stimulated insulin secretion (GSIS) was measured with a square-wave hyperglycemic clamp in the presence or absence of adrenergic receptor antagonists phentolamine (alpha) and propranolol (beta). IUGR fetuses were hypoglycemic and hypoxemic and had lower GSIS responsiveness (P < or = 0.05) than control fetuses. IUGR fetuses also had elevated plasma norepinephrine (3,264 +/- 614 vs. 570 +/- 86 pg/ml; P < or = 0.05) and epinephrine (164 +/- 32 vs. 60 +/- 12 pg/ml; P < or = 0.05) concentrations. In control fetuses, adrenergic inhibition increased baseline plasma insulin concentrations (1.7-fold, P < or = 0.05), whereas during hyperglycemia insulin was not different. A greater (P < or = 0.05) response to adrenergic inhibition was found in IUGR fetuses, and the average plasma insulin concentrations increased 4.9-fold at baseline and 7.1-fold with hyperglycemia. Unlike controls, basal plasma glucose concentrations fell (P < or = 0.05) with adrenergic antagonists. GSIS responsiveness, measured by the change in insulin, was higher (8.9-fold, P < or = 0.05) in IUGR fetuses with adrenergic inhibition than controls (1.8-fold, not significant), showing that norepinephrine suppresses insulin secretion in IUGR fetuses. Strikingly, in IUGR fetuses, adrenergic inhibition resulted in a greater GSIS responsiveness, because beta-cell mass was 56% lower and the maximal stimulatory insulin response tended (P < 0.1) to be higher than controls. This persistent norepinephrine suppression appears to be partially explained by higher mRNA concentrations of adrenergic receptors alpha(1D), alpha(2A), and alpha(2B) in a cohort of fetuses that were naïve to the antagonists. Therefore, norepinephrine suppression of insulin secretion was maintained, in part, by upregulating adrenergic receptor expression, but the beta-cells also appeared to compensate with enhanced GSIS. These findings may begin to explain why IUGR infants have a propensity for increased glucose requirements if norepinephrine is suddenly decreased after birth.

Pulmonary nocardiosis in cystic fibrosis.

BACKGROUND: The treatment of Nocardia species found in the sputum of cystic fibrosis patients is of unknown value. METHODS: We conducted a retrospective analysis of the impact of directed oral antibiotic therapy against Nocardia spp. isolated from the sputum of 17 cystic fibrosis patients over a 10-year period. Pulmonary Function Tests were used as the clinical indicator of the disease state and the data were analyzed by general linear mixed model statistics with univariate analysis. RESULTS: Pulmonary Function Test values of all patients studied showed no significant difference before, during, or after the antibiotic treatment period. Treatment groups did not differ from non-treatment groups. This held true for Forced Expiratory Volume over 1 s and Functional Vital Capacity analysis. In addition, individual patient analysis did not reveal any trends or outliers. CONCLUSIONS: Oral antibiotic therapy of cystic fibrosis patients colonized with Nocardia does not appear to affect clinical outcome. This suggests that deferring therapy may be an acceptable alternative and justifies conducting a future placebo controlled trial. In addition, this study model may be useful in analyzing the effect of therapy on other rare and difficult organisms, such as fungi and mycobacteria in the cystic fibrosis population.