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J I Labarta

Publications and source records attributed to J I Labarta.

10 recordsLinked to original sources

Childhood-onset congenital adrenal hyperplasia: long-term outcome and optimization of therapy.

Congenital adrenal hyperplasia is a general term applied to several disorders caused by inherited recessive defects of cortisol synthesis. The most common form is 21-hydroxylase deficiency, accounting for 95% of cases. The classical forms have an incidence of one in 15,000 and the non-classical forms about one in 1,000. The classical or severe phenotype presents in the newborn period or early infancy with virilization and adrenal insufficiency, with or without salt-losing; the non-classical or mild phenotype presents in late childhood or early adulthood with signs of hyperandrogenism. This wide range of clinical expression is explained by genetic variation. Although there is a certain amount of genotype-phenotype correlation, discrepancies have been described. During the last 30 years there has been a substantial improvement in diagnosis and treatment of this disease, and patients with CAH now reach adulthood. Treatment of this condition is intended to reduce excessive corticotropin secretion and replace glucocorticoids and mineralocorticoids as physiologically as possible. Clinical management is often complicated by periods of inadequately treated hyperandrogenism, iatrogenic hypercortisolism, or both. Long-term consequences in adult life may include short stature, obesity, diminished bone mass, gonadal dysfunction with low fertility rates and psychosexual dysfunction in females. New treatment approaches are under investigation, such as the use of anti-androgens, inhibitors of estrogen production and adrenalectomy for severely resistant cases.

Adrenal Hyperplasia, Congenital↗

Psychomotor and intellectual development of children born with intrauterine growth retardation (IUGR).

The possible impact of IUGR on the intellectual outcome of children born with IUGR gives special relevance to this condition. In order to determine the psychomotor and intellectual development of such children, we analyzed the evolution of 60 children through appropriate tests, along the years, and the possible influence of two factors, the socio-economic status of the family, and whether or not there was catch-up growth. Our results show a negative impact of IUGR on the intellectual outcome of these children, independent of catch-up growth, although those with catch-up growth showed better evolution. The socio-economic status plays a limited role only at older age. Those children followed longitudinally for 1 year did not show any amelioration of their IQ.

Adolescent↗

The need for specialized adolescence units.

Adolescence is the period of life of transition from childhood to adulthood; it includes not only sexual maturation but also physical and psychological maturation. The chronological age when this transition occurs is imprecise and not exactly defined. There are specific diseases that appear during this period of life that deserve specialized medical care. This article deals with the need to create specialized adolescence units with the direct participation of pediatricians. The transition through adolescence into adulthood is complicated by physical, psychological and social issues, and the transfer of adolescent patients to adult departments should be done gradually. There is a need for consensus guidelines about this issue.

Adolescent↗

Physical repercussions of childhood-onset growth hormone (GH) deficiency and hGH treatment in adulthood.

The aim of this study was to evaluate the physical condition of young adults with childhood-onset growth hormone deficiency (GHD) before and after 6 months of hGH therapy. Ten men and three women, aged 22.3 +/- 3.3 years, previously treated with hGH for 8.6 +/- 4.07 years at a dose of 0.5 IU/kg/week with a minimun of 2.5 years without treatment at the time of study, were studied. Nine patients presented isolated GHD and four patients had combined pituitary hormone deficiencies; they were treated with hGH at a dosage of 0.125 IU/kg/week for the first month and 0.25 IU/kg/week for the following 5 months. The tests performed were: exercise test, heart rate, rating of perceived exertion, blood lactate analysis, jump test and hand grip. Body composition was also analyzed using Holtain Body Analysis. Skinfold thickness was measured at four sites (triceps, biceps, subscapular and suprailiac). After 6 months of treatment a significant increase in lean body mass (42.0 +/- 7.72 to 46.2 +/- 8.01 kg, p = 0.004) and decrease in fat mass (19.6 +/- 10.01 to 16.1 +/- 10.79 kg, p = 0.01) were observed. The initial physical condition of these patients was lower than expected, and improved after treatment with an increase in maximum oxygen consumption from 2.0 +/- 1.2 to 2.33 +/- 0.68 l x min(-1) (p = 0.01). Maximum heart rate increased significantly from 189 +/- 14.8 to 193 +/- 11.7 beats x min(-1) (p = 0.03). No modifications were observed in anaerobic threshold (4 mmol x l(-1)). Only slight, non-significant increases were observed in jump and strength tests. We conclude that a) adults with childhood-onset growth hormone deficiency present a deficient physical condition and lower than expected for age and sex; b) this condition improves after 6 months of treatment, particularly in the aerobic aspect; c) changes observed in strength tests were discrete and of little significance; and d) the increase observed in lean body mass plays an important role in these changes. Further studies investigating GH action on maximum oxygen consumption are required, once its basic mechanism of action has been determined, either in the heart or peripheral factors.

Adult↗

Insulin-like growth factor binding protein-I levels are strongly associated with insulin sensitivity and obesity in early pubertal children.

In conditions associated with insulin resistance, insulin-like growth factor binding protein-I (IGFBP-I) levels have been shown to correlate inversely with insulin levels. Puberty is associated with insulin resistance and thus provides a model for comparing the relationship of IGFBP-I to both insulin levels and measures of insulin sensitivity. Our study population consisted of 104 healthy pubertal children, age 9.8-14.6 yr. Each subject had his/her insulin sensitivity (Si) assessed by the modified minimal model of Bergman, which employs a frequently sampled i.v. glucose tolerance test. Results showed that IGFBP-I levels were significantly higher in boys than in pubertally matched girls (P < 0.01). There was a strong positive correlation between IGFBP-I levels and Si (r = 0.65, P < 0.0001) and a weaker negative correlation with fasting insulin levels (r = -0.38, P < 0.0001). An inverse relationship was also found between IGFBP-I levels and body mass index (r = -0.46, P < 0.0001) and with IGF-I levels (girls only, r = -0.41, P < 0.003). Consequently, insulin sensitivity, obesity, and IGF-I are important predictors of IGFBP-I levels in pubertal children. It is possible that insulin-mediated suppression of IGFBP-I in obese children may increase free IGF-I levels and thus contribute to somatic growth. The same mechanism may operate in pubertal children, where insulin resistance and growth acceleration occur simultaneously.

Adipose Tissue↗

Immunoblot studies of the acid-labile subunit (ALS) in biological fluids, normal human serum and in children with GH deficiency and GH receptor deficiency before and after long-term therapy with GH or IGF-I respectively.

OBJECTIVE: The aims of this investigation were (a) to study the presence of immunoreactive forms of the acid-labile subunit (ALS) in different human biological fluids, (b) to define the age dependence of serum ALS in normal children and adults and (c) to compare the regulation of ALS by GH or IGF-I in children with GH deficiency (GHD) and GH receptor deficiency (GHRD) before and after 1 year of therapy with GH or IGF-I, respectively. DESIGN AND PATIENTS: Selected human biological fluids from different consenting volunteers and serum from 68 normal children and 5 adults were analysed. Four children diagnosed as GHD and 7 children diagnosed as GHRD were treated with recombinant human (rh) GH at a dosage of 0.05 mg/kg/day s.c. or rhIGF-I at a dosage of 120 micrograms/kg twice daily s.c., respectively, for 12 months. MEASUREMENTS: Immunoreactive forms of ALS were studied by Western immunoblot using a specific rabbit antiserum derived against synthetic human ALS and quantified by laser densitometry analysis. Serum from children with GHD or GHRD were sampled before and at 6 and 12 months of therapy; serum from these patients had been also assayed at baseline for determination of IGF-I and IGF binding protein (IGFBP)-3 by radioimmunoassay and immunoradiometric assay, respectively. RESULTS: An immunoreactive 85 kDa doublet of ALS was detected in serum, plasma, follicular, peritoneal and synovial fluid, but not in urine, seminal plasma, amniotic or extra-embryonic coelomic fluids. Assessment of serum from newborns to adults revealed an age dependence; the ALS doublet was low, but detectable, in newborns, increased during adolescence and remained constant in adulthood. ALS levels were significantly lower in GHD (P = 0.02) and in GHRD children (P = 0.001) than in age-matched controls. Treatment with rhGH in GHD children produced a 2.7-fold increase in serum ALS concentrations at 6 months of therapy (P = 0.01), which was maintained after 1 year of treatment (P = 0.006), leading to normalization of ALS concentrations. In contrast, administration of rhIGF-I to GHRD children failed to increase and normalize serum ALS levels either at 6 or 12 months of therapy. CONCLUSIONS: Immunoreactive forms of acid-labile subunit are present in serum and plasma, as well as in follicular, peritoneal and synovial fluids, suggesting that acid-labile subunit can either cross the capillary barrier or be secreted locally. Acid-labile subunit concentrations are age-dependent with a sharp increase during adolescence, and are reduced in GH deficient and GH receptor deficient children. While treatment with rhGH is able to increase and normalize acid-labile subunit concentrations in GH deficient children, therapy with rhIGF-I fails to increase serum acid-labile subunit levels in GH receptor deficient patients. These data suggest that acid-labile subunit is directly GH-regulated, and that IGF-I cannot increase acid-labile subunit levels, as assessed by Western immunoblot.

Adolescent↗

Evidence for insulin-like growth factor (IGF)-independent transcriptional regulation of IGF binding protein-3 by growth hormone in SKHEP-1 human hepatocarcinoma cells.

Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) is a polypeptide that forms a ternary complex with IGFs and an acid-labile subunit. The hormonal regulation of the components of this complex is highly controversial, and both IGF-I and GH have been shown to mediate the expression/synthesis of IGFBP-3. This study investigates the regulation of IGFBP-3 protein, measured by RIA and Western ligand blot, and messenger RNA (mRNA) expression, measured by Northern analysis and reverse transcriptase-PCR, in SKHEP-1 human hepatocarcinoma cells. SKHEP-1 cells significantly increased the IGFBP-3 concentrations in conditioned medium (CM) when treated with GH (0.1-10 ng/ml), IGF-I (1-100 ng/ml), or Des(1-3)-IGF-I (1-100 ng/ml) in a dose-dependent manner (>3-fold). The increase in IGFBP-3 protein concentrations in CM was accompanied by a corresponding increase in IGFBP-3 mRNA levels. Interestingly, time-course studies showed that the GH-induced increase in IGFBP-3 mRNA preceded the IGF-I-induced increase (6 h for GH-induced IGFBP-3 mRNA; 12 h for IGF-I-induced IGFBP-3 mRNA). The half-life of IGFBP-3 mRNA was evaluated after transcriptional arrest by treatment with a RNA polymerase II inhibitor (5,6-dichloro-1beta-D-ribofuranosylbenzimidazole), and was found to be 14-18 h and unaltered by GH or IGF-I treatment. The induction of IGFBP-3 by GH was not due to the indirect action of locally synthesized IGF-I, because 1) no immunoreactive IGF-I was detected in the CM of control or GH-treated cells; 2) Northern blots revealed no IGF-I mRNA expression in SKHEP-1 cells; 3) reverse transcriptase-PCR did not detect any expression of the IGF-I gene; and 4) time-course studies showed an earlier increase in IGFBP-3 mRNA after GH treatment than after IGF-I treatment. Thus, the results obtained in this study are consistent with an IGF-I-independent regulation of IGFBP-3 gene expression by GH.

Blotting, Western↗

IGF-II and IGF-binding proteins increase dramatically during rabbit pregnancy.

During pregnancy, changes in the IGF axis are associated with changes in maternal metabolism and nutrient repartitioning which are necessary to meet the demands of a growing conceptus. The aim of this study was to assess the IGF axis, maternal weight changes and food intake in female New Zealand White rabbits (n = 7) prior to breeding (day 0) and serially throughout pregnancy until term (day 30-31). The total weight of the pregnant does progressively increased from 4.03 +/- 0.06 kg (mean +/- S.E.M.) on day 0 to 4.47 +/- 0.07 kg on day 30 (P < 0.001). Maternal tissue mass (total weight minus estimated conceptus weight) increased until day 18, plateaued to day 22/23, and then significantly declined. On day 30, the maternal tissue mass was not significantly different from the non-pregnant value, such that the final increase in total weight was due to conceptus growth. Although the does were fed ad libitum, food intake did not change until day 29 when it decreased to approximately 50% of previous intake (P < 0.01). Maternal serum IGF-I was 499 +/- 32 ng/ml on day 0, reached a peak of 832 +/- 160 ng/ml on day 21 (P < 0.02), and then declined to 341 +/- 49 ng/ml on day 30. In contrast, serum IGF-II increased dramatically from a non-pregnant level of 85 +/- 14 ng/ml to 16,295 +/- 2488 ng/ml on day 23 (P < 0.001), and then rapidly declined (3335 +/- 954 ng/ml, day 30). Changes in serum IGF-binding proteins (IGFBPs) followed a pattern similar to IGF-II, as assessed by Western-ligand blotting. All IGFBPs, especially the 45-40 kDa IGFBP-3 doublet, increased dramatically between days 12 and 24 of pregnancy, and then declined towards term. In conclusion, we observed unique and dramatic changes in the maternal serum IGF axis that corresponded to periods of maternal weight gain and loss. The tissue source of IGFs and IGFBPs remains undetermined, although it is of note that the time when major changes in the IGF axis were first observed coincided with the time of functional change from yolk sac to placenta in the rabbit.

Animals↗

Constitutional delay in growth and puberty: a comparison of final height achieved between treated and untreated children.

Constitutional delay in growth and puberty (CDGP) is one of the principal causes of consultation due to short height. Frequently familial short stature is associated with the CDGP. The predicted final height is reached in the majority of the cases but some individuals do not achieve their target height. Poor growth, especially during the pubertal years, as well as a short or growth delayed mother are some of the negative factors for final outcome. Some prepubertal children show a transient diminished GH secretion that normalizes during puberty. Therapy with hGH or oxandrolone increases growth velocity but does not ameliorate final height. The psychosocial situation of the children is the most important condition to treat with testosterone, estrogens or oxandrolone. In view of the results hGH should not be administered routinely to these cases. It remains open which children could benefit from hGH therapy.

Body Height↗