Effect of propranolol plus exercise on melatonin and growth hormone levels in children with growth delay.

The pineal gland in humans is under both alpha- and beta-adrenergic control, although it seems that beta1-adrenoceptors are mainly implicated in melatonin secretion. In the present study, we evaluated the role of beta-adrenergic innervation on melatonin production and its relation with the production of growth hormone (GH). Thirty-four children (15 males and 19 females, mean age 10.5 +/- 0.8 years) from the University of Granada Hospital were studied. The children were included in a protocol for the evaluation of growth delay using the propranolol + exercise test. This standardized test allowed us to study simultaneously the role of an unspecific beta-adrenergic blocker such as propranolol and of an adrenergic stimulus such as exercise on the pineal production of melatonin. Changes in plasma levels of melatonin and GH were determined at basal, 120 and 140 min after the test was applied. Hormonal determinations were carried out by commercial radioimmunoassay kits previously standardized in our laboratory. The results show a significant decrease in plasma melatonin levels at 120 and 140 min after the test (P < 0.05), whereas GH levels increased significantly at 140 min (P < 0.001). The decrease of melatonin levels was a consequence of the test, since in a control group, the circadian decay of melatonin was significantly less pronounced (P < 0.05). These data suggest an inverse relationship between melatonin and GH after the propranolol + exercise test, and the reduction in melatonin may be related to its depletion by exercise-induced oxidative stress.

Comparison between tryptophan methoxyindole and kynurenine metabolic pathways in normal and preterm neonates and in neonates with acute fetal distress.

OBJECTIVE: To analyze the kynurenine and methoxyindole metabolic pathways of tryptophan in order to identify changes in premature neonates and in neonates suffering from fetal distress. METHODS: One hundred and twelve neonates were assigned to three groups: normal neonates (control group), preterm neonates (neonates born before the 37th gestational week) and neonates suffering from fetal distress. Each of these groups was then divided in two subgroups according to the time of birth corresponding with the time of blood sampling: a diurnal subgroup, comprising neonates whose blood was sampled between 0900 and 2100 h, and a nocturnal subgroup, comprising neonates whose blood was sampled between 2100 and 0900 h. Blood samples from the umbilical artery and vein were taken in the delivery room at birth from each neonate for measurement of melatonin, the main methoxyindole pathway metabolite. Urine samples were collected from 0900 to 2100 h (diurnal groups) and from 2100 to 0900 h (nocturnal groups), and the presence of kynurenic acid, xanturenic acid, 3-hydroxyantranilic acid, L-kynurenine and 3-hydroxykynurenine determined. RESULTS: The results show the existence of diurnal/nocturnal differences in the concentration of melatonin in cord blood and in the urinary excretion of kynurenines. In normal neonates, the production of methoxyindoles (determined as melatonin) is decreased during the day and increases at night, whereas production of kynurenines is high during the day, decreasing at night. In the fetal distress group, a significant increase in the umbilical artery concentration of melatonin was found. This group also showed a reduction in L-kynurenine concentrations in the diurnal and nocturnal groups, and an increase in xanturenic acid and 3-hydroxyantranilic acid during the day. Correlation and regression studies confirmed that the differences in the day/night pattern of the tryptophan metabolic pathways were greater in normal neonates than in the preterm and fetal distress groups. CONCLUSIONS: The results indicate the existence of an imbalance in tryptophan metabolites in preterm infants and those with fetal distress, blunting the normal diurnal/nocturnal rhythm of both melatonin and kynurenines.

[Changes in erythrocyte rigidity and neonatal relative viscosity during the adaptation of the newborn to extrauterine life. Observations on term and premature newborns]. / Modificaciones de la rigidez eritrocitaria y viscosidad relativa neonatal durante la adaptación del recién nacido a la vida extrauterina. Consideraciones en recién nacidos a término y pretérmino.

BACKGROUND: The deformability of the red blood cell is a important factor in the blood viscosity and it is related with the blood viscosity and it is modified by the plasma biochemical characteristics and the composition of hemoglobin in the red blood cell. In this study, we want to compare the rheologic characteristics in the blood of cord umbilical in term and preterm newborns during the first 24 hours of life and we want to evaluate that hemorheologic modifications are explained because of the different gestational age. METHODS: We studied 191 newborns in our maternity from 1989 until 1990. We analyzed four groups: In the first group (n = 40) of preterm newborn (gestational age < 37 weeks); in the second group (n = 72) of term newborns (gestational age > 37 weeks); the samples were obtained from umbilical artery immediately after the umbilical cord clamp; in the third group (n = 38) of preterm newborn and the fourth group of term newborns (n = 41) was studied during 24 hours after delivery. We analyzed the plasma viscosity, the viscosity of red blood cell (RBC) content and the RBC rigidity calculated by Taylor's coefficient. RESULTS: The RBC rigidity is greater during the post-delivery period, which could be in relation with the greater values of plasma viscosity and the RBC content during the postnatal period. The comparisons between umbilical cord of term and preterm newborn they did not show differences for the RBC content viscosity and the relative viscosity. The plasma viscosity of the umbilical cord was discretely greater in the term newborn though in meaning limits statistics. In umbilical cord the hematocrit does not defer significantly between term and preterm newborns. CONCLUSIONS: Following our data we can make firm that the RBC rigidity is increased after the delivery in term and preterm newborns and the greater relative viscosity observed in newborn to term during the first life extrauterine days in related fundamentally to the corporal liquids readjustment that occurs after of delivery.

Lipoproteins in pregnant women before and during delivery: influence on neonatal haemorheology.

AIMS: To investigate whether the lipid profile of pregnant women during parturition differs from the profile at previous stages of pregnancy and to determine the effects of maternal lipid changes on fetal or neonatal haemorheology. METHODS: Sixty pregnant women were studied, divided into two groups. Group 1 contained 30 women of mean age of 27 (SD 3) years and gestational age > 38 weeks in whom delivery had not yet begun; all these pregnancies followed an uncomplicated course and there was no evidence of any fetal pathology from previous obstetric examinations. All the women reached term and birth weight was 3340 (350) g. Group 2 contained women of mean age 26 (4) years, in whom delivery was ongoing, all of whose pregnancies reached term. The following variables were determined in all cases: total cholesterol, triglycerides, high density lipoproteins (HDL), low density lipoproteins (LDL), free fatty acids and phospholipids, and apoprotein A (apo-A) and apoprotein B (apo-B). Serum and plasma viscosity was measured with a capillary viscosimeter. RESULTS: The apo-B/apo-A and HDL/apo-A ratios increased during delivery, indicating that in pregnant women these atherogenic indices are raised during delivery compared with previous gestational stages. Significant correlation coefficients were obtained between maternal lipids (triglycerides, total cholesterol, LDL, total cholesterol/HDL, and LDL/HDL) and plasma viscosity in the neonate. CONCLUSIONS: Plasma atherogenic indices increase progressively until birth. These changes have implications for neonatal haemorheology because they cause an increase in plasma viscosity.