Growth Hormone Bioactivity and Levels of Growth Hormone, Growth Hormone–Binding Protein, Insulinlike Growth Factor I, and Insulinlike Growth Factor–Binding Proteins in Premature and Full-term Newborns During the First Month of Life

Radetti, Giorgio; Bozzola, Mauro; Paganini, Chiara; Valentini, R; Gentili, Lino; Tettoni, K.; Tatò, Luciano

doi:10.1001/archpedi.1997.02170390060011

Cited by 27 publications

(24 citation statements)

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“…It should be remembered that the Nb 2 cell bioassay measures lactogenic, as opposed to somatogenic, GH bioactivity; however, a good correlation has been shown between the results of this assay and the auxometric findings (18 -20). Both 20-kD and 22-kD serum levels at birth were shown to be significantly higher in preterm than in full-term neonates and adults and to rapidly decrease in the following weeks, as previously reported using conventional RIA (11). In only two premature babies with the lowest GA, very low levels of 20-kD and 22-kD forms were found, which both increased at 15 d of life.…”

Section: Discussionsupporting

confidence: 82%

“…Up to date, there is only one report (9), based on conventional RIA, concerning the secretion of these GH isoforms in the neonatal period, when the secretion of GH is peculiar. High GH serum levels are reported at birth (10, 11), particularly in the premature infant (11,12), which decrease significantly in the following months of postnatal life (13). The aim of this study was to verify with a highly sensitive assay (ELISA) the behavior of the 20-kD variant and its relationship with the 22-kD form and GH bioactivity in a group of premature neonates in the first 2 wk of life.…”

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Circulating GH Isoforms and GH Bioactivity in Preterm Neonates

et al. 2000

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Among the molecular variants of human GH, the monomeric 22-kD is the predominant isoform, whereas the 20-kD is the second most abundant isoform. Because little is known on the pattern of human GH isoforms in the early postnatal period, we evaluated serum levels of 22-kD GH by an immunofluorometric assay and of 20-kD GH by an ELISA using an anti-20-kD antibody, and measured GH bioactivity with the Nb 2 cell bioassay in 19 preterm neonates (gestational age, 32 Ϯ 0.5 wk; mean Ϯ SEM) on the fourth and 15th days of life. As control subjects, we studied 19 full-term neonates (gestational age, 39 Ϯ 0.3 wk) on the fourth day of life and 20 healthy adults, aged 20 Ϯ 0.3 y. Four-day-old preterm neonates showed significantly higher serum values of 20-kD GH (0.99 Ϯ 0.14 ng/mL) than full-term neonates (0.33 Ϯ 0.07 ng/mL; p Ͻ 0.001) and adults (0.09 Ϯ 0.02; p Ͻ 0.0001). Likewise, 22-kD GH and GH levels by Nb 2 cell bioassay were also significantly higher (p Ͻ 0.001) in preterm than in full-term neonates and young adults. A significant decrease (p Ͻ 0.01) in 20-kD, 22-kD, and Nb 2 -determined GH was observed in preterm neonates on the 15th day of life The percentage of the 20-kD isoform was similar in the preterm infants at the fourth and 15th day, in full-term infants, and in adults (2.7%, 2.7%, 2.8%, and 3.16%, respectively). Our results indicate that 20-kD GH serum levels change throughout life as regards total amount, but not as regards percentage. Abbreviations Nb 2 -GH, GH bioactivity evaluated by Nb 2 cell bioassay PI, ponderal index GA, gestational age hGH, human GH Serum GH is represented mainly by the 22-kD form and by several other monomeric size variants (1, 2). The 20-kD variant, which differs from the 22-kD form in that residues 32-46 are deleted (3), is reported to be the second most common circulating isoform (4, 5) and is believed to be produced by alternative splicing (6, 7). It has recently been shown that the 22-kD and the 20-kD forms are under the pituitary drive in normal and short children and that the serum levels of the 20-kD isoform parallel those of the 22-kD after pharmacologic stimuli as well as during spontaneous secretion (8). Up to date, there is only one report (9), based on conventional RIA, concerning the secretion of these GH isoforms in the neonatal period, when the secretion of GH is peculiar. High GH serum levels are reported at birth (10, 11), particularly in the premature infant (11,12), which decrease significantly in the following months of postnatal life (13). The aim of this study was to verify with a highly sensitive assay (ELISA) the behavior of the 20-kD variant and its relationship with the 22-kD form and GH bioactivity in a group of premature neonates in the first 2 wk of life. METHODS PatientsWe studied 19 healthy preterm neonates (10 boys, 9 girls; 32 Ϯ 0.5 wk gestational age) with a birth weight of 1587 Ϯ 123 g and length of 41.2 Ϯ 0.9 cm. For comparison, we studied 19 full-term neonates (11 boys, 8 girls; 39 Ϯ 0.3 wk) with a birth weight of 3372 Ϯ 106 g and length of 50 Ϯ 0...

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Circulating GH Isoforms and GH Bioactivity in Preterm Neonates

et al. 2000

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“…Since LH receptors are located in Leydig cells (or Leydig cell precursors), it is possible that a secretory product of these cells stimulated Sertoli cell inhibin B secretion. After birth, serum levels of GH and prolactin (PRL) are high, in particular during the first weeks of life (16,17). Furthermore, receptors for GH and PRL have been described in the testes (18).…”

Section: Discussionmentioning

confidence: 99%

Secretion of inhibin B by human prepubertal testicular cells in culture

Berensztein

Saraco²,

Belgorosky³

et al. 2000

European Journal of Endocrinology

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Objective: Inhibin B is a secretory product of Sertoli cells of the human testis. It has been reported that serum levels of inhibin B in infant boys, peaking at 3 months of age, exceed levels in adult men. The aim of this study was to evaluate inhibin B secretion in primary prepubertal mixed testicular cell cultures, prepared from testes collected at necropsy. Design and Methods: Cell cultures were divided into three age groups on the basis of differences in testicular histology: group 1 (n ¼ 7), 1-to 10-day-old newborns, group 2 (n ¼ 7), 1-to 9-month-old infants, and group 3 (n ¼ 8), 12-to 84-month-old children. Cells were maintained in culture for 6 days, harvested and counted. In some samples, during the last 4 days, cells were stimulated with 10 ng/ml highly purified human (h) LH (n ¼ 9), 2 ng/ml recombinant human (rh) FSH (n ¼ 9) or 50 ng/ml rhGH (n ¼ 4). On day 6, the secretion of inhibin B and testosterone into the medium was estimated in triplicate. Inhibin B was determined by ELISA and testosterone by RIA. Results: Median (range) inhibin B secretion was 465 (225-1007), 275 (107-298), and 58 (15-184) pg/million cells.24 h in groups 1, 2 and 3 respectively. A logarithmic transformation of these values was performed to normalize data. Mean Ϯ S.D. of transformed inhibin B secretion in group 1 was significantly higher than in group 2 or 3 (P < 0:005) and the values for groups 1 and 2 were significantly higher than that for group 3 (P < 0:005). No significant correlation between testosterone and inhibin B secretion into the medium was found when the 22 culture samples were analyzed as a whole. Inhibin B secretion was significantly increased after stimulation with highly purified hLH, rhFSH and rhGH (P < 0:05) and a significant positive correlation between inhibin B and testosterone was found under both hLH and rhFSH stimulation. Conclusions: It is concluded that cells collected from newborns have the highest capacity to secrete inhibin B in vitro, and that this capacity decreases with age during the first years of life. Since no data are available on serum inhibin levels in newborns, it is possible that concentrations at 3 months of age do not represent a post-natal peak but a declining level of high newborn values. As expected, FSH stimulated inhibin B secretion in culture. LH stimulation was probably mediated by paracrine factors secreted by interstitial cells. Finally, our results add new evidence of the involvement of GH in testicular maturation.

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“…This metabolic disturbance has been implicated in an increased rate of cardiovascular disease, fetal malformations, dementia, and neuropsychiatric symptoms among patients on AEDs (5-7 ). Homocysteine metabolism is dependent on four B vitamins as cofactors: The methylation of homocysteine to methionine requires folate and vitamin B 12 , and the irreversible transsulfuration to cysteine requires vitamin B 6 (8 ). The recycling of folate cofactors is dependent on vitamin B 6 and B 2 , and vitamin B 2 is necessary for activating vitamin B 6 to pyridoxal 5Ј-phosphate (PLP) (9 ).…”

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“…Vitamin B 2 and B 6 status thus may have an impact on tHcy concentrations in patients taking AEDs, but few studies have reported on this matter (3,4,10,11 ). The methionine loading test detects individuals with impaired homocysteine metabolism not detected by fasting Hcy concentrations alone and is often considered primarily a test of the transsulfuration pathway (1,8,12 ). We therefore determined the fasting and 6 h post-methionine loading (postload) plasma concentrations of thiols and B vitamins in patients taking AEDs.…”

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