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A Muñoz Hoyos

Publications and source records attributed to A Muñoz Hoyos.

11 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

[Serum transferrin receptor in healthy children].

BACKGROUND: Serum transferrin receptor (sTfR) is a reliable tool for assessing functional iron status and erythropoietic activity in adults, but little is known about its role in children. OBJECTIVE: To evaluate sTfR concentrations in healthy children and age and sex-related variations. A further aim was to determine the relationship of these concentrations with other iron parameters and with erythropoietin. PATIENTS AND METHODS: Blood samples from 155 healthy children aged 1-10 years old were obtained to determine sTfR, iron status indices and erythropoietin. The sTfR/ferritin ratio and the sTfR-ferritin index (sTfR/log ferritin) were calculated. Iron deficiency and increased erythropoiesis were eliminated. RESULTS: Values of sTfR, the sTfR/ferritin ratio and the sTfR-F index were 1.94 0.41mg/L (95 % CI: 1.14-2.74 mg/L), 83 40.3 (95 % CI: 4-162) and 1.4 0.36 (95 % CI: 0.69-2.1) respectively. No significant sex-related differences were found. Children aged 1-2 years old showed the highest sTfR levels. sTfR was directly related to erythrocyte count (r: 0.17; p < 0,03), hemoglobin level (r: 0.16; p < 0.05) and total iron binding capacity (r: 0.258; p < 0,001). In the multiple linear regression analysis, the best predictors of sTfR concentrations were log erythropoietin (p < 0.016) and total iron binding capacity (p < 0.0001). CONCLUSIONS: sTfR concentrations are elevated in children due to increased iron requirements for growth. In healthy children sTfR concentrations are related to erythropoietic activity and intracellular iron requirements. The current data are useful as a standard reference for healthy children.

Child↗
PubMed2000

Seizure recurrence after a first unprovoked seizure in childhood: a prospective study.

PURPOSE: To study the risk of recurrence after a first unprovoked seizure in childhood. METHODS: All consecutive patients aged less than 14 years with one or more unprovoked seizures who were attended between January 1, 1987, and June 1, 1996, were included in a prospective study. Clinical features of patients attended after a first seizure and those attended after two or more seizures were compared. Recurrence risk in both groups was estimated by Kaplan-Meier curves. Univariate and multivariate analyses of the potential predictors of recurrence risk were performed for the group of patients attended after a first seizure using the Cox proportional hazards model. RESULTS: Included in the study were 217 children. Kaplan-Meier estimate of recurrence risk was 64% at 5 years, when only patients being attended after a first epileptic seizure were included, compared with 74% when all patients were included. Significant differences in several clinical features were found between patients attended after a first seizure and those attended after two or more seizures. Univariate and multivariate analyses showed that in the overall cohort of patients attended after a first seizure, a symptomatic etiology increased the risk of recurrence, whereas a patient age of 3 to 10 years decreased this risk. In particular, the recurrence risk was 96% at 2 years for symptomatic seizures, compared with 46% for idiopathic/cryptogenic seizures. In the group of patients with idiopathic/cryptogenic seizures, an abnormal electroencephalogram and the occurrence of seizures during sleep increased the recurrence risk, whereas a patient aged 3 to 10 years reduced it. In the group of patients with symptomatic etiology, univariate analysis revealed that there was a lower recurrence risk for patients aged 3 to 10 years. This last finding was not maintained, however, in multivariate analysis. CONCLUSIONS: The recurrence risk depends on the inclusion criteria for enrolling patients. Several factors enable us to predict the recurrence risk after a first unprovoked seizure; the most important of these factors is the etiology of the seizures.

Adolescent↗
PubMed2000

[Health status of gypsy and non-gypsy children in a health district in Granada].

AIM: To evaluate the health status of gypsy and non-gypsy children and to determine how far stereotypes need to be eradicated in order to improve decision-making. The aim of this investigation originated in the observation of different behaviors in the population of a health district in Granada, Spain, and in the apparent concentration of certain diseases in the pediatric population of the gypsy minority. MATERIALS AND METHODS: Data from the clinical histories and variables of the mother and child health program of the Iznalloz Health Center were analyzed and compared. Of these clinical histories 149 (38.40%) belonged to gypsy children and 239 (61.59%) belonged to non-gypsy children. RESULTS: Outstanding variables were:a) the start of breastfeeding and its continuation until the third month were the same for both groups; b) gypsy children were up to 3.53 times more likely to be admitted to the neonatal unit than non-gypsy children; c) metabolic illness or degenerative illness accounted for 1.4%, and d) incomplete follow-up was up to 3.24 times more likely in gypsy children than in non-gypsy children.

Adolescent↗
PubMed1996

[Pineal functioning (melatonin levels) in healthy children of different ages. An update and the value of pineal gland study in pediatrics].

BACKGROUND: Classically, the function of the pineal gland involved the regulation of several endocrine and non-endocrine functions, such as seasonal breeding, biological rhythm synchronization and the sleep/wake cycle. The study of the pineal gland has not a new increasing interest due to the recent discovery that melatonin is the most potent antioxidant compound known to date. MATERIAL AND METHODS: We present here the data of aMT levels (mean +/- SD, pg/ml) measured by RIA in healthy children grouped by age and time of sample extraction. The group differences are evaluated by a mean comparison test. RESULTS: The results showed that plasma levels of aMT in cord blood reflect both the aMT levels and their circadian rhythm seen in the mother, without significant differences between umbilical artery and vein. In children between 18 months and 6 years of age, aMT concentrations at 09.00 reaches a maximum of 60.8 +/- 100.58. This value significantly decreased in children between 6-8 years old (35.54 +/- 9.17, p < 0.001), with a more significant decrease in children 8-13 years old (25.28 +/- 7.16, p < 0.01). However, in children 13-15 years of age, aMT concentrations increased to 31.14 +/- 8.29 pg/ml (p < 0.01). CONCLUSION: Our data support the existence of a functional pineal gland during the neonatal period, although it lacks the rhythmic secretion of aMT. From the preschool stage, children show a significant decrease in aMT concentration, except during the pubertal period when there is a small increase in aMT levels. In this paper we also review the available information about pineal function, specifically in regards to the relationship between pineal-melatonin and CURRENT PEDIATRICS in order to better understand the infant physiology and physiopathology related to this area.

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↗
PubMed1983

[Epidemiologic aspects of visceral leishmaniasis in the Province of Granada].

Authors make a retrospective study in 18 children with kala-azar, considering in every case the following epidemiological aspects: age, sex, situation, time of the year and lethality. They have also studied the vector of this disease in some points in Granada and after an adequate study concluded that the main vector of the kala-azar in the investigated zone is "Phlebotomus perniciosus". They have detected as well a new species in Spain, "Plebotomus longicuspis", with a slight epidemiological interest. Finally both investigations are compared finding two zones in Granada (the town and the coast) where most of the cases of kala-azar, are agglutinated and where main species of the vectors were found.

Animals↗