Fetal and maternal plasma leptin levels during the second half of normal pregnancies and those with Down syndrome.

OBJECTIVE: To assess the correlation of fetal and maternal plasma leptin concentrations during the second half of uncomplicated, euploid pregnancies and to compare these values with those obtained from pregnancies with Down syndrome. METHODS: Paired maternal venous and fetal umbilical blood samples were obtained during cordocentesis in 36 uncomplicated, euploid pregnancies and nine pregnancies with Down syndrome fetuses. Concentrations of leptin were measured by sensitive radioimmunoassay. RESULTS: Among pregnancies with euploid fetuses, there was significant correlation between both fetal and maternal leptin levels and gestational age (r = 0.464, p = 0.005 and r = 0.629, p < 0.001, respectively). Fetal plasma leptin concentrations also correlated with maternal levels (r = 0.485, p = 0.003), but fetal levels were significantly lower than maternal values (mean 2.12 +/- 0.44 ng/ml vs. 17.79 +/- 5.48 ng/ml, respectively; p < 0.001). Down syndrome fetuses had significantly lower fetal plasma leptin levels than gestational age-matched control euploid fetuses (0.72 + 0.54 ng/ml vs. 2.12 + 0.44 ng/ml; p < 0.002). However, there was no difference in maternal leptin concentrations between euploid and Down syndrome pregnancies. CONCLUSION: In euploid pregnancies, fetal leptin levels were significantly lower than the corresponding maternal values but increased across gestation. Down syndrome was associated with significantly lower fetal leptin levels.

Amino acid (GAS:BCAA) ratios in plasma and gut contents of short-term protein depleted rats.

The ratio of total concentrations or molar ratios (moles/1,000 amino acid residues) of three non-essential amino acids (glycine, alanine, serine-GAS) and three essential-branched chain amino acids (valine, isoleucine, leucine-BCAA) were investigated in rat systemic and portal vein plasma and jejunal and ileal gut contents after feeding normoprotein (NP) or protein-free (PF) diets for 7 days. Amino acid analysis of gut content showed that the GAS:BCAA ratio was not significantly altered by the PF diet either in the jejunum or in the ileum. On the contrary, the PF diet, caused a three and four-fold increase in this ratio in the portal and systemic plasma, respectively. The situation was produced by the higher concentrations of GAS, which remained near control levels (portal plasma) or exceeded these values (systemic plasma), in contrast to the decreasing levels of BCAA found in both plasmas of the PF group.

Effects of protein-free diet in amino acid homeostasis of rat blood plasma and gut contents.

Amino acids in rat systemic and portal vein plasma and jejunal and ileal gut contents after 7 days of feeding normoprotein (NP) and protein-free diet (PF) are investigated. Amino acid analyses revealed that ingestion of PF diet resulted in unusual amino acid patterns in both plasmas. Thus, while the levels and/or molar ratios of all indispensable amino acids were significantly decreased, those of several gluconeogenetic amino acids, especially of glycine and alanine, were increased in both plasmas, but particularly in portal. By contrast, the molar ratios of the majority of amino acids in jejunal and ileal contents were not changed by PF diet.