GHBP Levels Research Articles

Exercise combined with lysine-inositol vitamin B12 promotes height growth in children with idiopathic short stature

ObjectiveThis study was aimed to systematically determine the effect of exercise combined with lysine-inositol vitamin B12 (VB12) therapy on the height of children with idiopathic short stature (ISS). MethodsSixty children with ISS were randomly divided into observation and control groups (N = 30). Each group was given lysine-inositol VB12 oral solution (10 mL bid). Simultaneously, the observation group exercised following the “ISS exercise instruction sheet”. The height (H), growth velocity (GV), height standard deviation score (HtSDS) and other indicators were compared after 6 and 12 months of intervention, respectively. After 12 months of intervention, the biochemical indicators of the two groups, together with the correlation between the average days of exercise per week and average minutes of exercise per day, GV and serum growth hormone were analyzed. ResultsAfter 6 and 12 months of treatment, the GV, serum GHRH, GHBP, GH, IGF-1, and IGFBP-3 levels in the observation group were significantly higher than those in the control group, and HtSDS was significantly lower than that in the control group (P<0.01). After 12 months of treatment, the height of the observation group was significantly higher than that of the control group (P<0.05). There was no significant difference in the biochemical indicators between two groups (P>0.05). Average days of exercise per week and average minutes of exercise per day were positively correlated with GV and GHBP levels. Serum GHRH, GH, IGF-1, and IGFBP-3 levels were negatively correlated. Average minutes of exercise per day were negatively correlated with GV and GHBP levels. Serum GHRH, GH, IGF-1, and IGFBP-3 levels were positively correlated. ConclusionRegular and moderate stretching exercises combined with lysine-inositol VB12 can effectively promote height growth of children with ISS, which is clinically safe. The mechanism promotes serum GHRH, GHBP, GH, IGF-1, and IGFBP-3 levels.

Correlation Study between Levels of Gastrin, Serum IGF-1, and GHBP and Growth and Development in Children with Short Stature Based on Big Data Analysis.

To analyze the correlation between the levels of gastrin, serum IGF-1, and GHBP and growth and development in children with short stature (SS) using the big data. By means of retrospective analysis, the clinical data of 42 children with SS admitted to our hospital from October 2020 to October 2021 were selected as the study group, while 30 children with the healthy physical examination results in the corresponding period were selected as the control group to measure the growth and development indices and the levels of gastrin, serum IGF-1, and GHBP. The Pearson correlation analysis was used for the relationship between the levels of gastrin, serum IGF-1, and GHBP and growth and development indices in children with SS, and the targeted intervention measures were formulated by the analysis of experimental data. Compared with the study group, the height, weight, and bone mineral density (BMD) Z-scores of children in the control group were obviously higher (P < 0.001). The levels of gastrin, serum IGF-1, and GHBP in the study group were markedly lower than those in the control group (P < 0.05). The Pearson correlation analysis showed that the gastrin, serum IGF-1, and GHBP of children were positively correlated with growth and development indices (P < 0.001). The levels of gastrin, serum IGF-1, and GHBP in children were distinctly improved after treatment (P < 0.05). The gastrin, serum IGF-1, and GHBP are closely related to the SS, and the effective clinical intervention can better improve the above indicators of children to promote their growth and development.

Idiopathic short stature and growth hormone sensitivity in prepubertal children.

We compared growth hormone sensitivity to an insulin-like growth factor I (IGF-I) generation test in children with idiopathic short stature (ISS) and of normal stature (NS) across the birthweight range. Forty-six prepubertal children (~7.1years) born at term were studied: ISS (n=23; 74% boys) and NS (n=23; 57% boys). Children underwent a modified IGF-I generation test with recombinant human growth hormone (rhGH; 0.05mg/kg/d) over four consecutive days. Hormonal concentrations were measured at baseline and day 5. Children with idiopathic short stature were 1.90 SDS lighter (P<0.0001) but had 4.5% more body fat (P=0.0007) than NS children. Overall, decreasing birthweight SDS across the normal range (-1.9 to +1.5 SDS) was associated with lower percentageIGF-I response to rhGH stimulation in univariable (r=0.45; P=0.002) and multivariable models (β=24.6; P=0.006). Plasma IGF-I concentrations rose in both groups with rhGH stimulation (P<0.0001). GHBP levels (P=0.002) were suppressed in ISS children (-19%; P=0.029) but increased among NS children (+18%; P=0.028), with contrasting responses also observed for leptin and IGFBP-1. Further, the increase in insulin concentrations in response to rhGH stimulation was ~3-fold greater in NS children (142% vs 50%; P=0.006). A progressive decrease in birthweight SDS was associated with a reduction in GH sensitivity in both NS and ISS children. Thus, the lower IGF-I response to rhGH stimulation in association with decreasing birthweight indicates that the ISS children at the lower end of the birthweight spectrum may have partial GH resistance, which may contribute to their poorer growth.

Intermittent hypoxia suppression of growth hormone and insulin-like growth factor-I in the neonatal rat liver

ObjectivesExtremely low gestational age neonates with chronic lung disease requiring oxygen therapy frequently experience fluctuations in arterial oxygen saturation or intermittent hypoxia (IH). These infants are at risk for multi-organ developmental delay, reduced growth, and short stature. The growth hormone (GH)/insulin-like growth factor-I (IGF-1) system, an important hormonal regulator of lipid and carbohydrate metabolism, promotes neonatal growth and development. We tested the hypothesis that increasing episodes of IH delay neonatal growth by influencing the GH/IGF-I axis. DesignNewborn rats were exposed to 2, 4, 6, 8, 10, or 12 hypoxic episodes (12% O2) during hyperoxia (50% O2) from P0-P7, P0-P14 (IH), or allowed to recover from P7-P21 or P14-P21 (IHR) in room air (RA). RA littermates at P7, P14, and P21 served as RA controls; and groups exposed to hyperoxia only (50% O2) served as zero IH controls. Histopathology of the liver; hepatic levels of GH, GHBP, IGF-I, IGFBP-3, and leptin; and immunoreactivities of GH, GHR, IGF-I and IGF-IR were determined. ResultsPathological findings of the liver, including cellular swelling, steatosis, necrosis and focal sinusoid congestion were seen in IH, and were particularly severe in the P7 animals. Hepatic GH levels were significantly suppressed in the IH groups exposed to 6–12 hypoxic episodes per day and were not normalized during IHR. Deficits in the GH levels were associated with reduced body length and increase body weight during IHR suggesting increased adiposity and catchup fat. Catchup fat was also associated with elevations in GHBP, IGF-I, leptin. ConclusionsIH significantly impairs hepatic GH/IGF-1 signaling during the first few weeks of life, which is likely responsible for hepatic GH resistance, increased body fat, and hepatic steatosis. These hormonal perturbations may contribute to long-term organ and body growth impairment, and metabolic dysfunction in preterm infants experiencing frequent IH and/or apneic episodes.

Antisense oligomer therapy directed at the GH receptor is associated with reduction in circulating GHBP levels

Antisense oligomer therapy directed at the GH receptor is associated with reduction in circulating GHBP levels

Growth hormone receptor gene expression in puberty.

The mechanisms regulating the synergic effect of growth hormone and other hormones during pubertal spurt are not completely clarified. We enrolled 64 females of Caucasian origin and normal height including 22 prepubertal girls, 26 pubertal girls, and 16 adults to evaluate the role of Growth Hormone/Insulin-like growth factor-I axis (GH/IGF-I) during the pubertal period. In these subjects both serum IGF-I and growth hormone binding protein levels, as well as quantitative growth hormone receptor (GHR) gene expression were evaluated in peripheral lymphocytes of all individuals by real-time PCR. Our results showed significantly lower IGF-I levels in women (148±10 ng/ml) and prepubertal girls (166.34±18.85 ng/ml) compared to pubertal girls (441.95±29.42 ng/ml; p<0.0001). Serum GHBP levels were significantly higher in prepubertal (127.02±20.76 ng/ml) compared to pubertal girls (16.63±2.97 ng/ml; p=0.0001) and adult women (19.95±6.65 ng/ml; p=0.0003). We also found higher GHR gene expression levels in pubertal girls [174.73±80.22 ag (growth hormone receptor)/5×10(5) ag (glyceraldehyde 3-phosphate dehydrogenase)] compared with other groups of subjects [women: 42.52±7.66 ag (growth hormone receptor)/5×10(5) ag (glyceraldehyde 3-phosphate dehydrogenase); prepubertal girls: 58.45±0.18.12 ag (growth hormone receptor)/5×10(5) ag (glyceraldehyde 3-phosphate dehydrogenase)], but the difference did not reach statistical significance. These results suggest that sexual hormones could positively influence GHR action, during the pubertal period, in a dual mode, that is, increasing GHR mRNA production and reducing GHR cleavage leading to GHBP variations.

Plasma growth hormone-binding protein levels in Atlantic salmon Salmo salar during smoltification and seawater transfer.

Specific growth hormone (GH)-binding protein (Ghbp) was purified from Atlantic salmon Salmo salar and rainbow trout Oncorhynchus mykiss plasma with immunoprecipitation and characterized in cross-linking studies using autoradiography and western blots. The size of the Ghbp was estimated to be c. 53 kDa. A radioimmunoassay was established to measure Ghbp in salmonids, using antibodies specific against the extracellular segment of the S. salar growth hormone receptor 1 (grh1; GenBank AY462105). Plasma Ghbp levels were measured in S. salar smolts in fresh water and after transfer to seawater (SW; experiments 1 and 2), and in post-smolts kept at different salinities (0, 12, 22 and 34) for 3 months (experiment 3). A transient increase in plasma Ghbp, which lasted for 1 month or less, was noted in smolts after transfer to SW. Concomitantly, plasma GH and gill Na(+) -K(+) -ATPase activity increased during smoltification (in experiment 2). No difference in plasma Ghbp was evident between post-smolts kept at different salinities, although the fish kept at salinity 34 had higher plasma GH than the group kept at salinity 22 and higher hepatic ghr1 expression than post-smolts kept at salinity 12. This suggests that plasma Ghbp regulation may respond to salinity changes in the short term. The lack of correlation between Ghbp, plasma GH and hepatic ghr1 expression in the long-term post-smolt experiment indicates that Ghbp levels may be regulated independently of other components of the endocrine GH system in salmonids.

Association of serum components of the GH-IGFs-IGFBPs system with GHR-exon 3 polymorphism in normal and idiopathic short stature children

ObjectiveTo investigate the possible association of circulating components of GH-IGFs-IGFBPs system with the GHR-exon 3 genotype in normal and idiopathic short stature (ISS) children. DesignDescriptive, cross-sectional study in normal and ISS children. Subjects and methods192 normal and 81 ISS children (age: 5–17years) were included. Serum IGF-I, IGFBP3, ALS and GHBP levels were measured. GHR-exon 3 polymorphism (GHRd3) was analyzed by multiplex PCR assay. Normal and ISS children were divided according to GHR-exon 3 genotype: homozygous for the full-length GHR isoform (GHRfl) and carriers of one or two copies of the GHRd3 allele. ResultsGHRd3 genotype distribution (fl:fl/fl:d3/d3:d3,%) in normal (60:34:6) and ISS (64:32:4) was similar and reached Hardy–Weinberg equilibrium. ISS children had significantly reduced levels of GHBP and GH-dependent factors as compared to controls (p<0.0001). Within the normal group, homozygous carriers of the GHRfl allele had significantly higher GHBP serum levels than those with one or two copies of the GHRd3 allele (Mean±SEM; GHRfl: 3.2±0.2 vs GHRd3: 2.7±0.2nmol/L, p=0.04). No other significant association with GHR exon 3 polymorphism was found in either the normal or the ISS groups. ConclusionsGHR exon 3 polymorphism is distributed similarly in normal and ISS children, however only normal homozygous children for GHRfl allele showed higher GHBP levels. The lack of association between GHBP and GHR polymorphism in ISS children might be related to the heterogeneity of this group, where potential defects in GH receptor action may result in partial GH insensitivity.

Familial Short Stature Caused by Haploinsufficiency of The Insulin-like Growth Factor 1 Receptor Due to Nonsense-Mediated mRNA Decay

Context: Progesterone has been associated with promoting growth of uterine leiomyomas. The mechanisms involved remain unclear. Objective: In this study we investigated the activation of the AKT pathway and its downstream effectors, GSK3b and FOXO1 by progesterone as a mechanism of proliferation and survival of leiomyoma cells. Inhibitors of the AKT pathway were used to demonstrate the role of PI3K, AKT and FOXO1 in contributing to cell proliferation and apoptosis. Results: Treatment of leiomyoma cells with R5020 over a period of 72h resulted in higher cell numbers compared to untreated cells. When cells were treated with 100nM R5020 for 1h and 24h, the levels of phospho(Ser 473)-AKT increased. This increase was inhibited when cells were co-treated with RU486. Treatment of leiomyoma cells with a PI3K inhibitor, LY294 dramatically decreased levels of phospho(Ser 473)-AKT, despite R5020 treatment. In addition to increased phospho(Ser 473)-AKT levels, R5020 treatment resulted in an increase in phospho(Ser 256)-FOXO1 and phospho-GSK3b. Inhibition of AKT using API-59 decreased proliferation and cell viability even in the presence of R5020. Higher concentrations of API-59 induced apoptosis of leiomyoma cells even in the presence of R5020. Psammaplysene A increased nuclear FOXO1 levels and did not affect cell proliferation but induced apoptosis of leiomyoma cells. Conclusions: The progestin, R5020, can rapidly activate the AKT pathway. Inhibition of the AKT pathway inhibits cell proliferation and promotes apoptosis of leiomyoma cells. Familial Short Stature Caused by Haploinsufficiency of The Insulin-like Growth Factor 1 Receptor Due to Nonsense-Mediated mRNA Decay Peng Fang, I. David Schwartz, Betty D. Johnson, Michael A. Derr, Charles T. Roberts Jr., Vivian Hwa, and Ron G. Rosenfeld (J Clin Endocrinol Metab, published February 24, 2009, 10.1210/jc.2008-1903) ABSTRACT Background: Insulin-like growth factor-I (IGF-I), essential for normal human growth in utero and postnatally, mediates its effects through the IGF-I receptor (IGF1R), a widely expressed, cell-surface tyrosine kinase receptor. Five cases of heterozygous mutations in the IGF1R gene have been identified in patients with varying degrees of intrauterine and postnatal growth retardation. Objective: Analysis of the IGF1R gene in a short-statured patient and his affected family members. Patient: The male patient, with a height of –3.1 SDS (age of 12 years), had normal circulating levels of GHBP, IGF-I and IGFBP-3.Background: Insulin-like growth factor-I (IGF-I), essential for normal human growth in utero and postnatally, mediates its effects through the IGF-I receptor (IGF1R), a widely expressed, cell-surface tyrosine kinase receptor. Five cases of heterozygous mutations in the IGF1R gene have been identified in patients with varying degrees of intrauterine and postnatal growth retardation. Objective: Analysis of the IGF1R gene in a short-statured patient and his affected family members. Patient: The male patient, with a height of –3.1 SDS (age of 12 years), had normal circulating levels of GHBP, IGF-I and IGFBP-3. His mother (-4.6 SDS), one of his siblings (-1.94 SDS), and several other maternal family members were also short-statured. Results: The patient, his mother and the short-statured sibling carry a novel heterozygous 19-nucleotide duplication within exon 18 of the IGF1R gene, which introduces a premature termination codon at codon 1106 of the IGF1R open reading frame on one allele. Analyses of the primary dermal fibroblasts derived from the patient and family members indicated that the IGF1R mRNA expressed from the mutant allele was degraded through the Nonsense-Mediated mRNA Decay (NMD) pathway, resulting in reduced amount of wild-type IGF1R protein, and subsequently, diminished activation of the IGF1R pathway. Conclusions: The mutation results in haploinsufficiency of IGF1R protein due to Nonsense-Mediated mRNA Decay, and is associated with familial short stature. Mol Endocrinol, April 2009, 23(4):584–585 mend.endojournals.org 585

Novel nonsense mutation (p.Y113X) in the human growth hormone receptor gene in a Brazilian patient with Laron syndrome

To date, about sixty different mutations within GH receptor (GHR) gene have been described in patients with GH insensitivity syndrome (GHI). In this report, we described a novel nonsense mutation of GHR. The patient was evaluated at the age of 6 yr, for short stature associated to clinical phenotype of GHI. GH, IGF-1, and GHBP levels were determined. The PCR products from exons 2-10 were sequenced. The patient had high GH (26 microg/L), low IGF-1 (22.5 ng/ml) and undetectable GHBP levels. The sequencing of GHR exon 5 disclosed adenine duplication at nucleotide 338 of GHR coding sequence (c.338dupA) in homozygous state. We described a novel mutation that causes a truncated GHR and a loss of receptor function due to the lack of amino acids comprising the transmembrane and intracellular regions of GHR protein, leading to GHI.

Cytokines and growth factors during and after a wrestling season in adolescent boys.

Brief periods of aerobic exercise training lead to reductions, rather then the expected increases in circulating IGF-I. We hypothesized that intense exercise training in adolescents initially leads to simultaneous increases in proinflammatory cytokines and decreases in activity of the GH/IGF-I axis; and that as exercise training proceeds, levels of proinflammatory cytokines become reduced, and a rebound in IGF-I ensues leading to the higher IGF-I levels. To test this, we evaluated the GH/IGF-I axis and levels of inflammatory cytokines (IL-6, TNF-alpha, IL-1beta, IL-1ra), body composition, and fitness in 13 healthy adolescent boys (mean age 15.9 +/- 0.3 yr) over the course of a high-school wrestling season. Subjects were tested preseason, midseason (6 wk), peak season (12-14 wk), and 4 wk postseason. No significant weight loss was noted throughout the season. During the wrestling season (mid and peak) both total (P < 0.046) and free (P < 0.002) IGF-I levels decreased, whereas proinflammatory cytokines (IL-1ra, P < 0.005; IGFBP-1, P < 0.013; and IGFBP-2, P < 0.025) increased. GHBP (P < 0.018) levels also decreased during the season. In the postseason, there were significant increases in GHBP, and free and total IGF-I, whereas proinflammatory cytokines decreased. An initial catabolic-type hormonal response occurs with intense exercise training in adolescents. This is followed by a rebound in circulating growth factors when the period of heavy training ceases.

Body Composition and Circulating Levels of Insulin, Insulin-Like Growth Factor-Binding Protein-1 and Growth Hormone (GH)-Binding Protein Affect the Pharmacokinetics of GH in Adults Independently of Age

The aim of our study was to scrutinize the association among age, body composition, and GH status in healthy adults. Using two-step, primed constant infusions of GH during suppression of endogenous GH secretion with octreotide in a group of 26 healthy nonobese men [mean age, 37.3 yr (range, 22-55 yr); body mass index, 24.6 +/- 0.4 kg/m(-2)] we investigated the contributions of age, body composition, insulin, and binding proteins to the variability in the pharmacokinetics and acute actions of GH. All subjects were investigated twice, with the infusion rates of GH calculated according to either total body weight or intraabdominal fat mass. Body composition was determined using computed tomography and bioimpedance measurements. There was no correlation between age and body weight, yet strong positive correlations were observed between age and intraabdominal fat area (r = 0.78; P < 0.0001) and waist to hip ratio (r = 0.71; P < 0.0001) and to a lesser degree to sc fat area (r = 0.42; P < 0.03). The between-subject variability in steady state GH levels was significantly larger when GH was administered per cm(2) intraabdominal fat area than per kg BW (P < 0.001). During primed constant infusions of GH at rates of 1.5 and 3.0 microg/kg x h, the corresponding MCRs of GH were 148.8 +/- 5.4 and 89.8 +/- 2.4 ml/min x m(-2), respectively, and the MCRs were inversely related to the achieved steady state GH levels (P < 0.0001). The MCR was unrelated to age, but was negatively correlated to baseline concentrations of IGF-binding protein-1 (IGFBP-1; r = -0.53, P < 0.01) and positively correlated to basal levels of insulin (r = 0.46; P < 0.05), GH-binding protein (GHBP; r = 0.52; P < 0.01), IGFBP-3 (r = 0.47; P < 0.05), and total body fat (r = 0.44; P < 0.05). GH infusion caused significant changes in the concentrations of IGF-I, free fatty acids, GHBP, IGFBP-1, and insulin, but none of these effects was correlated to age. Based on our results we conclude that 1) the clearance of GH is concentration dependent; 2) the pharmacokinetics and acute effects of GH are not affected by age per se; and 3) basal levels of insulin, IGFBP-1, and GHBP as well as age-related changes in body composition are important predictors of GH pharmacokinetics.

Acquired growth hormone resistance in patients with chronic heart failure: implications for therapy with growth hormone

OBJECTIVES We aimed to determine whether growth hormone (GH) resistance is present in patients with chronic heart failure (CHF) and whether it may be linked to the biochemical response to GH treatment. BACKGROUND Acquired GH resistance is a feature of severe illness, in particular, cachexia. In patients with CHF, the response to GH therapy appears to be variable. METHODS Biochemical markers of the GH-insulin-like growth factor-I (IGF-I) axis were compared in 21 cachectic patients with CHF, 51 noncachectic patients and 26 healthy control subjects. In separate studies, the predictive value of baseline biochemical variables for the IGF-I response to GH treatment was analyzed. RESULTS Cachectic patients showed an increase of total GH and immunologically intact GH (p ≤ 0.0002) and a decrease of GH-binding protein (BP) (p = 0.005), IGF-BP3 (p = 0.01) and IGF-I (p = 0.06), compared with noncachectic patients. Similar changes were found when the cachectic group was compared with the control group. No differences were found between noncachectic patients and control subjects. Levels of GH-BP correlated with the IGF-I/GH ratio in all subgroups (all p ≤ 0.002). Baseline GH-BP levels were related to the increase of IGF-I levels in response to GH treatment in patients with CHF after 24 h (r = 0.83, p = 0.005; n = 9; study 2), 44 days (r = 0.52, p = 0.007; n = 25; study 3) and 96 days (r = 0.54, p = 0.006; n = 24; study 3). CONCLUSIONS Most cachectic and some noncachectic patients with CHF show features of acquired GH resistance. The principal predictors of the biochemical features of GH resistance and of the poor biochemical response to short-term and longer-term GH treatment are GH-BP plasma levels. The presence of GH resistance is potentially a major factor determining the response to GH therapy in patients with CHF.

Mutations of the Growth Hormone Receptor Found in Japanese Short Children.

We present here two mutations of the growth hormone (GH) receptor (GHR) gene in Japanese patients with GH insensitivity syndrome (GHIS) or idiopathic short stature (ISS). One is a heterozygous point mutation of the donor splice site in intron 9 of the GHR gene in 2 siblings with GHIS, whose serum GHBP levels were high. The same mutation was also found in their mother as well. The analysis of RNA from the peripheral leukocytes revealed complete skipping of exon 9 from one allele, but not the other, in the GHR cDNA and appearance of a premature stop codon in exon 10. This mutation caused truncation of GHR with a dominant negative effect on GH signaling, which is probably responsible for their short stature and high serum GHBP levels. The other mutation is a heterozygous missense mutation, C422F, in the intracellular domain of GHR. Although this mutation was previously reported in a patient with GH insensitivity syndrome (GHIS), it has not been clear whether this mutation causes GH insensitivity. To clarify the effect of this mutation on GH signal transduction, mutant GHR was expressed in CHO cells and its functional properties were investigated. Neither GH-induced tyrosine phosphorylation of STAT5b nor STAT5-mediated transcriptional activation were found in GHR-C422F-expressing cells. In addition, the analysis of genotypes and phenotypes of this family revealed that a C422F mutation was found in family members showing normal height, indicating that the C422F missense mutation of GHR is not responsible for short stature.

DECREASED INSULIN-LIKE GROWTH FACTOR-I RECEPTOR SITES ON CIRCULATING MONONUCLEAR CELLS FROM CHILDREN WITH ACUTE LEUKEMIA

Insulin-like growth factor-I (IGF-I) is a known mitogen for various cell types, including those of the hematopoietic cell system. To study the role of IGF-I in the neoplastic process of leukemia in children, the authors have determined the number of IGF-I binding sites on circulating mononuclear cells of children with acute leukemia as compared to normal children, using binding assays. The IGF-I binding sites per cell on peripheral mononuclear cells of children with leukemia decreased compared to those of the control group (411 +/- 73 and 1334 +/- 227, respectively, p < .001), while their affinity increased (Kd = 0.14 +/- 0.04 and 0.43 +/- 0.16, respectively, p = .05). Furthermore, in the patients, the number of the IGF-I binding sites was significantly lower in the subgroup of the peripheral mononuclear cells, which included lymphocytes and monocytes, as compared to their number in the peripheral blast cells (254 +/- 43.6 and 536 +/- 98.6, respectively, p = .02). A significant reduction was found in serum GHBP levels in the patients as compared to the controls (28.21 +/- 1.93 and 35.83 +/- 2.90, respectively, p = .02), while serum IGF-I and growth hormone levels were similar in patient and control groups. These results suggest a possible involvement of IGF-I in childhood acute leukemia, but further studies are needed to establish whether IGF-I plays a role in this disease.

The study of spontaneous GH secretion after 36-h fasting distinguishes between GH-deficient and normal adults.

Within an appropriate clinical context, GH deficiency (GHD) in adults can only be diagnosed biochemically by provocative testing. The evaluation of IGF-I, IGFBP-3 and even of spontaneous GH secretion do not establish the diagnosis of adult GHD. In fact, remarkable overlaps between normal and GHD adults have been reported for all these parameters. On the other hand, it is well known that even short-term fasting stimulates GH secretion in normal subjects. The aim of our study was to determine the effects of 36 h fasting on 8-h diurnal GH, insulin and glucose levels as well as on basal IGF-I, IGFBP-3, acid-labile subunit (ALS), IGFBP-1, GHBP and free fatty acid (FFA) levels. We studied 9 GHD adults (GHD, 8 males, 1 female; age, mean +/- SEM: 37.6 +/- 2.3 years, body mass index (BMI): 24.5 +/- 1.0 kg/m2) and 20 age-matched normal subjects (NS) as controls (13 males, 7 females; age: 28.9 +/- 0.6 years, BMI: 21.6 +/- 0.4 kg/m2). In all subjects we studied the effects of 36 h fasting on 8-h daytime GH, insulin and glucose levels (assay every 30 min from 0800 h to 1600 h) as well as on basal IGF-I, IGFBP-3, ALS, IGFBP-1, GHBP and FFA levels. Before fasting, basal mean IGF-I, IGFBP-3 and ALS levels in GHD were lower (P < 0. 0001) than in NS. IGFBP-1, GHBP and FFA levels were similar in both groups. Before fasting mean GH concentration (mGHc) in GHD was lower (P < 0.05) than in NS (0.4 +/- 0.2 vs. 2.2 +/- 0.6 mu/l) but with a clear overlap between the 2 groups (range 0.4-0.8 vs. 0.4-6.8 mu/l). After fasting, both in GHD and NS basal IGF-I, IGFBP-3, ALS and GHBP levels did not change significantly. On the other hand, in both GHD and in NS IGFBP-1 was increased (P < 0.0001) to a similar extent, while FFA increased in NS more (P < 0.01) than in GHD. Fasting significantly increased mGHc in NS (12.0 +/- 1.2 mu/l, P < 0.0001) but not in GHD (0.6 +/- 0.2 mu/l). After fasting, no overlap was present between GHD and NS (0.4-1.6 vs. 2.4-20.8 mu/l, respectively). Mean glucose and insulin concentrations over 8 h in GHD and NS in basal conditions were similar and were reduced to the same extent in both groups. Our findings demonstrate that after short-term fasting, the study of spontaneous GH secretion distinguishes between GH-deficient adults and normal subjects; this phenomenon occurs before significant changes in IGF-I and IGFBP-3 levels. These results suggest that the assessment of spontaneous GH secretion could be useful for the diagnosis of adult GH deficiency only after short-term fasting.

Effect of Growth Hormone (GH) Treatment on The Levels of GHBP in GH Deficient Children (GHD)

Effect of Growth Hormone (GH) Treatment on The Levels of GHBP in GH Deficient Children (GHD)

Alterations in the growth hormone-insulin-like growth factor axis in insulin dependent diabetes mellitus.

The growth hormone (GH)-insulin-like growth factor (IGF) axis and insulin are major anabolic effectors in promoting weight gain and linear growth. These two anabolic systems are interlinked at many levels, thus abnormalities in one of these systems effect the other causing disordered metabolic homeostasis. Insufficient portal insulinization in insulin dependent diabetes mellitus (IDDM) results in hepatic GH resistance and increased production of IGF-binding proteins-1 (IGFBP-1) and IGFBP-2. GH resistance is reflected by decreased hepatic IGF-I production. In addition, changes in other GH-dependent proteins are also observed in IDDM. Increased proteolysis of IGFBP-3 results in reduction of intact IGFBP-3. Serum ALS levels are also slightly diminished in untreated diabetic patients. Hepatic resistance to GH is, at least in part, caused by diminished GH receptors as reflected by diminished circulating GHBP levels. In addition, there is also evidence from experimental and human studies suggesting post-receptor defect(s) in GH action. As a result of these changes, circulating total and free IGF-I levels are decreased during insulinopenia. Lack of negative feed-back effect of IGF-I on GH secretion causes GH hypersecretion which increases hyperglycemia by decreasing sensitivity to insulin. GH hypersecretion in poorly controlled diabetic patients may play a role in the pathogenesis of diabetic vascular complications. Most of these abnormalities in the GH-IGF axis in diabetes are reversed by effective insulinization of the patient. Addition of IGF-I treatment to insulin in adolescents with IDDM allows correction of GH hypersecretion, improves insulin sensitivity and glycemic control, and decreases insulin requirements. The effect of IGF-I treatment on diabetic complications has yet to be seen.

Growth hormone-insulin-like growth factor-I axis in adult insulin-dependent diabetic patients: evidence for central hypersensitivity to growth hormone-releasing hormone and peripheral resistance to growth hormone.

The aim of this study was to assess the GH-IGFI axis, GH receptor availability, as reflected by the levels of GH-BP, and the amount of GH-dependent IGFBP-3 in adult IDDM patients with different degrees of metabolic control. Thus, 10 adult well-controlled IDDMs (HbA1 7.8 +/- 0.4%), 10 adult non-ketotic poorly controlled IDDMs (HbA1 13.3 +/- 7%) and 14 sex- and age-matched healthy controls were subjected to two intravenous GH-RH stimulation tests with 0.1 and 1.0 microg/kg body weight respectively, and a plasma IGF-1 generation test induced by the administration of hGH. Poorly controlled IDDM patients exhibited an exaggerated GH response to 1.0 microg/kg of GH-RH when compared to healthy control subjects. Low fasting plasma IGF-1 levels and a blunted IGF-1 response to exogenously administered hGH were also found in poorly controlled IDDMs when compared to the healthy control group. GH-BP levels were significantly lower in IDDMs than in normal controls, and correlated positively with the IGF-1 generation capacity after hGH. Serum IGFBP-3 levels measured by RIA were similar in IDDM and control groups. Good glycemic control for 5.7 +/- 0.9 months did not correct the above mentioned abnormalities of the GH-IGF-1 axis. Our findings suggest that IDDM is associated with a diminished availability of GH receptors and synthesis of IGF-1. GH might then increase as a compensatory mechanism, further down-regulating liver GH receptors, and thus perpetuating the initial abnormality.

Tissue distribution, turnover, and glycosylation of the long and short growth hormone receptor isoforms in rat tissues.

Two isoforms of the GH receptor, the full-length receptor (GHRL) and a short isoform (GHRS) that lacks the transmembrane and intracellular domains of GHRL, have been analyzed in rat tissue extracts by Western blotting and immunoprecipitation. Although quantitative estimates of GHRS and GHRL based on coprecipitation of [125I]GH indicated similar amounts of both isoforms in tissue extracts, the 110 kDa band corresponding to GHRL was generally not detected on Western blots without enrichment by immunoprecipitation. Two bands with electrophoretic mobilities corresponding to 38 and 42 kDa were present in extracts prepared from liver, muscle, and adipocytes. Western blots of the GH binding protein in rat serum also revealed two bands, but these had electrophoretic mobilities corresponding to 44 and 52 kDa. After digestion by endoglycosidase F, a single band with an electrophoretic mobility corresponding to 31 kDa was detected in samples from adipocytes, liver or serum, indicating that GHRS retained in tissues is glycosylated less extensively than that in rat serum. Digestion with neuraminidase indicated that the smaller glycoproteins in tissue extracts lack sialic acid residues that are present in serum samples. Furthermore, endoglycosidase H degraded GHRS in liver extracts to a 31 kDa band but did not degrade serum samples, suggesting that tissues retain a high mannose form of GHRS. The abundance of GHRS or GHRL in tissues from male, virgin female, and pregnant rats was estimated from the amount of 125I-GH that was bound to each isoform after immunoprecipitation. Liver contained more than 10 times as much GHRS per gram of tissue as fat or muscle. In liver, muscle, and fat, the amount of GHRS exceeded that of GHRL, sometimes by as much as 6-fold. GHBP levels in serum of females exceeded those in males, and rose even higher in pregnant females. The abundance of GHRS in all tissue extracts paralleled serum levels. In muscle and fat, the levels of GHRL did not differ in male, female and pregnant rats, whereas in liver, the pattern was similar to the GHRS pattern. In all tissues, pools of GHRS exceeded those of GHRL by a factor that grew larger as tissue and serum levels increased. The half life of GHBP in serum was estimated to be 2.4 h in rats treated with cycloheximide, whereas that of GHRS was 20 min in liver and 8.5 h in fat. These results suggest that GHRS is synthesized in liver 8 times faster than it is released into serum, whereas synthesis in fat is less than 30% of the rate at which it is released into serum by all tissues. Therefore, liver appears to be the major source of GHBP in serum. Although secretion into the circulatory system accounts for little or perhaps none of its turnover in some tissues, GHRS pools in tissues do appear to be regulated, suggesting that GHRS may function primarily in the cells in which it is synthesized.