The GnRH system : importance for precocious puberty in children

We discuss here the secular early onset of puberty in children, the central mechanisms of puberty as well as the clinical aspects of central precocious puberty in children. How to suspect it, how to explore it and how to treat it are the main topics of this articleAprès avoir rappelé les mécanismes centraux de la puberté, nous nous focalisons sur les aspects cliniques de la puberté précoce centrale chez l’enfant. Comment la suspecter, comment l’explorer, comment la traiter : voilà les points qui sont développés dans cet articl

Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

Groupe 4 : traitement substitutif de l’insuffisance surrénale

International audienceno abstract

Review Article Bone Health Should Be an Important Concern in the Care of Patients Affected by 21 Hydroxylase Deficiency

Copyright © 2010 Anne Bachelot et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Osteoporosis has been an understandable concern for children and adult patients with congenital adrenal hyperplasia (CAH) who may receive or have received supraphysiological doses of glucocorticoids. Some previous reports on bone mineral density (BMD) in adult CAH patients showed no significant differences in BMD between patients with CAH and controls, but others have found lower BMD in CAH patients. In reports documenting the BMD reduction, this outcome has been attributed to an accumulated effect of prolonged exposure to excess glucocorticoids during infancy and childhood. We recently conducted a trial to establish the role of the total cumulative glucocorticoid dose on BMD. We established for the first time that there was a negative relationship between total cumulative glucocorticoid dose and lumbar and femoral BMD. Women might benefit from the preserving effect of estrogens compared to men. BMI (Body Mass Index) also appeared to protect patients from bone loss. In light of this, physicians should bear in mind the potential consequences of glucocorticoids on bone and therefore adjust the treatment and improve clinica

Deletion of P399_E401 in NADPH cytochrome P450 oxidoreductase results in partial mixed oxidase deficiency

P450 oxidoreductase (POR) is the electron donor for all microsomal P450s including steroidogenic enzymes CYP17A1, CYP19A1 and CYP21A2. We found a novel POR mutation P399_E401del in two unrelated Turkish patients with 46,XX disorder of sexual development. Recombinant POR proteins were produced in yeast and tested for their ability to support steroid metabolizing P450 activities. In comparison to wild-type POR, the P399_E401del protein was found to decrease catalytic efficiency of 21-hydroxylation of progesterone by 68%, 17α-hydroxylation of progesterone by 76%, 17,20-lyase action on 17OH-pregnenolone by 69%, aromatization of androstenedione by 85% and cytochrome c reduction activity by 80%. Protein structure analysis of the three amino acid deletion P399_E401 revealed reduced stability and flexibility of the mutant. In conclusion, P399_E401del is a novel mutation in POR that provides valuable genotype-phenotype and structure-function correlation for mutations in a different region of POR compared to previous studies. Characterization of P399_E401del provides further insight into specificity of different P450s for interaction with POR as well as nature of metabolic disruptions caused by more pronounced effect on specific P450s like CYP17A1 and aromatase

Characterization of a novel CYP19A1 (aromatase) R192H mutation causing virilization of a 46,XX newborn, undervirilization of the 46,XY brother, but no virilization of the mother during pregnancies.

BACKGROUND P450 aromatase (CYP19A1) is essential for the biosynthesis of estrogens from androgen precursors. Mutations in the coding region of CYP19A1 lead to autosomal recessive aromatase deficiency. To date over 20 subjects have been reported with aromatase deficiency which may manifest during fetal life with maternal virilization and virilization of the external genitalia of a female fetus due to low aromatase activity in the steroid metabolizing fetal-placental unit and thus high androgen levels. During infancy, girls often have ovarian cysts and thereafter fail to enter puberty showing signs of variable degree of androgen excess. Moreover, impact on growth, skeletal maturation and other metabolic parameters is seen in both sexes. OBJECTIVE AND HYPOTHESIS We found a novel homozygous CYP19A1 mutation in a 46,XX girl who was born at term to consanguineous parents. Although the mother did not virilize during pregnancy, the baby was found to have a complex genital anomaly at birth (enlarged genital tubercle, fusion of labioscrotal folds) with elevated androgens at birth, normalizing thereafter. Presence of 46,XX karyotype and female internal genital organs (uterus, vagina) together with biochemical findings and follow-up showing regression of clitoral hypertrophy, as well as elevated FSH suggested aromatase deficiency. Interestingly, her older brother presented with mild hypospadias and bilateral cryptorchidism and was found to carry the same homozygous CYP19A1 mutation. To confirm the clinical diagnosis, genetic, functional and computational studies were performed. METHODS AND RESULTS Genetic analysis revealed a homozygous R192H mutation in the CYP19A1 gene. This novel mutation was characterized for its enzymatic activity (Km, Vmax) in a cell model and found to have markedly reduced catalytic activity when compared to wild-type aromatase; thus explaining the phenotype. Computational studies suggest that R192H disrupts the substrate access channel in CYP19A1 that may affect binding of substrates and exit of catalytic products. CONCLUSION R192H is a novel CYP19A1 mutation which causes a severe phenotype of aromatase deficiency in a 46,XX newborn and maybe hypospadias and cryptorchidism in a 46,XY, but no maternal androgen excess during pregnancy

Group 2: Adrenal insufficiency: screening methods and confirmation of diagnosis.

A diagnosis of adrenal insufficiency should be suspected in the presence of a number of non-specific symptoms (fatigue, anorexia, weight loss, hypotension, hyponatremia and hyperkalemia amongst adrenal causes of insufficiency). The diagnosis should be considered in case of pituitary disease or a state of shock. Treatment should be commenced immediately without waiting for confirmation from biochemical tests, which rely on cortisol level at 8am (expected to be low) and on ACTH level (expected to be high in the case of primary adrenal insufficiency). If these tests are inconclusive, a Synacthen test should be carried out. The threshold limits are provided as a guide. Low plasma cortisol and normal to low plasma ACTH indicates a pituitary origin for the deficiency. In this situation, the Synacthen test can give a false normal result, and if this adrenal insufficiency is strongly suspected, an insulin hypoglycemia test or metyrapone (Metopirone) test should be carried out. In children younger than 2yr, hypoglycemia, dehydration and convulsions are frequently observed and in young girls, virilization is suspect of congenital adrenal hyperplasia . The circadian rhythm of cortisol is not present until after 4months of age and the Synacthen test is the only one that is feasible. In children older than 2yrs, the signs and diagnostic methods are the same as in the adult. Cessation of corticosteroid treatment is a frequent circumstance however there is little published data and no evidence for definitive guidelines. After ceasing a short period of corticosteroid treatment, patient education is all that is required. After longer treatment, consensus leaves the choice up to the physician, between educating the patient and prescribing hydrocortisone in case of stress, or prescribing low daily dose hydrocortisone and evaluating the ACTH axis over time until normal function is recovered.[Groupe 2 : insuffisance surrénale : méthodes de dépistage et confirmation du diagnostic] Le diagnostic d’insuffisance surrénale doit être évoqué devant des symptômes non spécifiques (fatigue, anorexie, amaigrissement, hypotension, hyponatrémie, hyperkaliémie dans les causes surrénaliennes…). Il faut la rechercher devant une maladie hypophysaire. Il faut y penser aussi devant un état de choc. Le traitement doit être débuté sans attendre la confirmation biologique qui repose sur le dosage du cortisol à 8 heures (que l’on attend abaissé) et de l’ACTH (que l’on attend élevée dans les causes surrénaliennes). Ces dosages sont complétés dans les situations limites par un test au Synacthène. Des seuils sont donnés à titre indicatif. Devant un cortisol abaissé, l’ACTH normale ou basse indique l’origine hypophysaire du déficit. Dans cette situation, le test au Synacthène peut être faussement normal et si la suspicion est forte, il faut réaliser une hypoglycémie insulinique ou un test à la Metopirone®. Chez le jeune enfant, l’hypoglycémie, la déshydratation, les convulsions sont fréquentes, une virilisation est évocatrice chez la fille d'hyperplasie surrénale congénitale. Le rythme circadien du cortisol ne prend place qu’après l’âge de 4 mois. Le test au Synacthène est donc le seul réalisable à cet âge. Chez l’enfant après 2 ans, les signes d’appel et les méthodes diagnostiques sont les mêmes que chez l’adulte. Le sevrage d’une corticothérapie est une circonstance fréquente pour laquelle les données de la littérature manquent. Apres arrêt d’une corticothérapie courte, seule l’éducation du patient est nécessaire. Pour les traitements longs, le consensus laisse le choix au prescripteur entre éducation du patient et prescription d’hydrocortisone en cas de stress ou prescription d’une petite dose d’hydrocortisone quotidienne et évaluation itérative de l’axe corticotrope jusqu’à récupération de l’axe