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E Narbona López

Publications and source records attributed to E Narbona López.

12 recordsLinked to original sources
PubMed2002

[Puberty and melatonin].

BACKGROUND: Melatonin is the main hormone secreted by the pineal gland and secretion is maximal at night. Although researchers disagree, numerous data suggest that elevated melatonin levels during the prepubertal age maintain the hypothalamic-pituitary-gonadal axis in quiescence, thus exerting an inhibitory effect on pubertal development. The decrease in serum melatonin with advancing age activates hypothalamic pulsatile secretion of gonadotropin-releasing hormone and consequently the reproductive axis, which results in the onset of puberty. OBJECTIVE: To evaluate urinary melatonin levels in children of different ages and the characteristics of its rhythmic excretion and to determine whether puberty is associated with a significant reduction in urinary melatonin levels. MATERIAL AND METHODS: Thirty-two children were studied (17 boys and 15 girls). Concentrations of 24-h urinary melatonin were quantified by radioimmunoassay in daytime samples (collected between 9.00 and 21.00) and nighttime samples (collected between 21.00 and 9.00 on the following day). Blood levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, testosterone and dehydroepiandrosterone sulfate (DHEAS) were calculated. Circadian rhythms and melatonin secretion in the various Tanner stages were assessed (ANOVA). RESULTS: No significant differences were found between day- and nighttime secretion of melatonin among boys (daytime melatonin: 1.38 0.52 pg/ml; nighttime melatonin: 6.92 2.06 pg/ml) and girls (daytime melatonin: 1.15 0.43 pg/ml; nighttime melatonin: 11.41 4.32 pg/ml). Highly significant differences were found (p < 0.001) between the day and night rates of melatonin secretion in both genders. Highly significant differences (p < 0.001) were also found in day-, nighttime and total secretion among the different Tanner stages. Comparison among groups revealed a significant decrease in secretion rates in stages I and II in both boys and girls. Melatonin significantly decreased with age in both sexes (lineal relationship). This decrease was greater at night. No relationship was found between the secretion of melatonin and estradiol, testosterone, LH, FSH and DHEAS. CONCLUSIONS: Melatonin secretion follows a circadian pattern, with greater secretion at night. The change in this rhythm was significantly greater in girls, due to greater nighttime secretion. Secretion significantly decreases in Tanner stages I and II with subsequent decreases in the later stages.

Adolescent↗
PubMed2001

[Intrauterine dwarfism and dysmorfic features. A case of Russel-Silver syndrome].

Russel-Silver syndrome is characterized by severe intrauterine growth retardation and is the most characteristic intrauterine dwarfism syndrome. In addition to short stature, low birth weight and reduced postnatal growth, this syndrome is characterized by features such a relative macrocephaly, a typical craniofacial appearance, asymmetry of the body and other abnormalities. Recent studies on developmental delay in these children have shown that most require special education. Attempts to explain the mechanism underlying this condition have been unsuccessful. Recent studies suggest a genetic cause, mainly uniparental disomy 7, although definitive data are lacking. We report a characteristic case of Russel-Silver syndrome: a newborn with fetal growth retardation, the craniofacial features described by Russel, relative macrocephaly, asymmetry of the body and very low weight increase.

Abnormalities, Multiple↗
PubMed1990

[Plasma concentration of atrial natriuretic peptide, vasopressin and aldosterone in the umbilical cord blood: its relation to perinatal asphyxia].

Aldosterone, vasopressin (AVP) and atrial natriuretic factor (ANF) plasmatic concentrations were determined in cord arterial blood from 42 newborns to term: 29 healthful and 13 with perinatal asphyxia. Control group showed plasmatic levels (pg/dl) AVP, aldosterone and ANF significantly lower than perinatal asphyxia newborns group (AVP: 2.27 +/- 1.43 vs 4.26 +/- 2.86; aldosterone: 1.113 +/- 384.79 vs 1,540.38 +/- 595.96; ANF: 2.27 +/- 1.43 vs 4.26 +/- 2.86, respectively (p less than 0.05). We found an inverse correlation between umbilical arterial pH vs AVP, aldosterone and AFN, and a direct correlation between ANF vs aldosterone. Perinatal asphyxia induces secretion of the three studied hormonal factors, likely as a physiologic mechanism of fetal adaptation to hydroelectrolytic and hemodynamic changes which occur during the asphyxia.

Aldosterone↗
PubMed1987

[Serum vitamin E in well-nourished and malnourished infants].

Vitamin E (tocopherol) concentrations in blood plasma were determined in 48 infants and correlated with their nutritional status. Infants were divided into two groups as following: group I (n : 12) estimated well-nourished, and group II (n : 36) appreciated undernourished. Clinical nutritional status was evaluated according to their weight, height and skinfold thickness of triceps percentiles. Plasma vitamin E levels were analysed by a modification of the spectrophotometric micro-technique of Fabiank et al. (using 0.2 ml of plasma). There was difference in serum tocopherol levels between two groups: 1.21 (0.21) mg/dl: mean (+/- SEM) in group I in front of 1.84 (0.18) mg/dl in group II (0.10 greater than p greater than 0.05). On the other hand, vitamin E concentrations were correlated with the skinfold thickness of triceps percentiles by a logarithm curve: y = 2.25-0.31 1n X (r: 0.35, p less than 0.02). Probably, serum vitamin E levels do not reflect the tissue store status in undernourished infants without malabsorption.

Female↗
PubMed1986

[Branched-chain amino acids: indicators of fetal nutritional status].

Both nutritive state for Rohrer's ratio (Rr) and serum aminoacids (aa) (Chromatospek J-180) of the umbilical cord have been analyzed and correlated in two groups of the newborns: G-I (n: 12) preterm infants with an adequated weight for their gestational age (Re greater than 10 percentile) and G-II (n: 8) small for-date term infants (Rr less than 10 p). Ratios of the serum aa (total aa, no essential aa, NE/E, Ala/Thr, Whitehead's ratio (Wr), Ala/Leu, Ala/BCA, Gly/Val, Ser + Gly + Ala/BCA) were more elevated in G-II than those one of the G-I. We have shown a single correlation between Wr and Rr (r. much greater than 0.48, p less than 0.025) in G-I and between BCA Rr (r. much greater than 0.88, p less than 0.0025) in G-II; furthermore, we have proved a good correlation between the week of gestation and sum of BCA (r. much greater than 0.53, p less than 0.05) in the former that have not been observed among the latter which had BCA more increased than G-I (p less than 0.050). Some speculations about the role that could play the BCA in the energetic metabolism of the small-for-date infants are made; on the other hand, the BCA can give help to distinguish between premature or pseudopremature among infants weighing 2.500 g or less a birth.

Amino Acids, Branched-Chain↗
PubMed1984

[Tryptophan metabolism in children with epilepsy].

Authors measured urinary excretion of tryptophan derivatives (kynurenine way) in 13 healthy and 15 epileptic children, modifying the technique qualitatively and quantitatively. In both groups, they measure tryptophan metabolites before and after L-tryptophan overload, the dosage being 100/mg/kg of body weight. They found higher tryptophan derivative values in the group suffering a epilepsy.

Adolescent↗
PubMed1983

[Cancer and adolescence].

Since 1977, 64 children were diagnosed with cancer in the Department of Pediatrics of the University of Granada. Incidence and mortality rates from specific tumor types are discussed. Most common malignant neoplasms of children are: 1. Leukemia (36.3%). 2. Tumors of central nervous system (10.7%). 3. Lymphoma, and tumors of sympathetic nervous system (19.9%). 4. Soft tissue (6.1%). 5. Kidney (7.6%). 6. Bone (4.6%). Most of the male excess (1.9:1, p less than 0.01) is accounted for by acute lymphocytic leukemia, and central nervous system tumors. It is evident that about one-half of all children diagnosed currently with a malignant disease will survive for a long period. Psychosocial aspects of cancer in the young are commented. This paper examines how patients, family members and medical staff feel and behave in response to occurrence of cancer in adolescent.

Adolescent↗