Pharmacological manipulation of height: qualitative review of study populations and designs.

OBJECTIVE: Various substances that can have an important effect on height are increasingly available. However, research into pharmacological manipulation of height in children has been criticized. There are concerns about diagnostic criteria; about the medical, ethical, and economic ramifications of modulating growth in children with no endocrinological abnormalities; and about biased results due to weak study designs. The authors reviewed articles published since Jan. 1, 1995, to characterize recent research into this area. METHODS: 70 peer-reviewed articles published in 18 journals in 1995 describing effects of hormonal interventions to affect height were reviewed. Study population, intervention, main purpose (safety, physiology, or therapeutic effect), and methodology were examined. The search was expanded after 1995 to list randomized controlled trials (RCTs) investigating pharmacological manipulation in children and its effect on ultimate height in adults. RESULTS: The inexpensive and brief androgen therapy for pubertal delay has been examined in RCTs, but expensive, long-term treatments to alter final adult height in children have rarely been subjected to RCTs. Some outcome reports pooled subjects with different causes of short stature. Documentation of growth hormone deficiency is problematic. CONCLUSIONS: There is a lack of RCTs in which target populations and growth outcomes are explicitly defined. Further research into overcoming barriers to relevant RCT studies is needed.

Growth hormone therapy for non-growth hormone-deficient children with short stature.

A summary of the majority of the available uncontrolled studies of 322 children with idiopathic short stature treated with growth hormone showed that the final height attainment over predicted adult height was only +2.85 cm (+0.49 SD score). Furthermore, a summary of seven studies reported that the spontaneous outcome in children with untreated idiopathic short stature was more than +1 SD score in final height compared to height at presentation; patients with delayed puberty spontaneously gained more than +2 SD score as adults. Recent reevaluations have concluded that short stature is not associated with clinically significant psychologic morbidity, and the psychologic outcome in response to growth hormone treatment of the short normal child showed no discernable difference in psychologic benefit, despite a difference in height gained. A recent editorial has strongly advised against the expanded use of growth hormone in the normal short child.

How do we best measure growth hormone action?

Growth hormone (GH) is a powerful anabolic hormone with a broad spectrum of action that has been assessed with three general parameters: auxological to assess the growth response; biochemical to measure anabolic effects; and body composition. In childhood, linear growth response is assessed with height, short-term changes in height velocity (HV), and attainment of final adult height, which may not be concordant. In both children and adults, the biochemical indices utilized to predict and/or monitor response to GH therapy have included: (1) nonspecific indices: glucose, insulin, urea, protein synthesis, lipid metabolism, and lipoproteins; (2) more specific indices of the GH-IGF axis: GH binding protein, IGF-I, IGFBP-3, and acid-labile subunit; or (3) indices of bone and mineral metabolism: calcium, phosphate, bone alkaline phosphatase, osteocalcin, propeptides of procollagen type I and III, and bone mineral content. For body composition, body mass index, total body % fat, total body or extracellular water, and bone mineral density have been addressed most frequently. Modest changes with wide variability have been observed with most measurements. GH dose is a very significant positive factor for all parameters. Few of the currently available tests can reliably predict and/or monitor response to GH therapy. Of these, serum IGF-I appears to offer the best integrated indicator of the action of GH throughout all age groups.

Effect of sleep deprivation on the growth hormone response to the alpha-3 adrenergic receptor agonist, clonidine, in normal subjects.

One night's sleep deprivation (SD) increased the growth hormone (GH) response to clonidine (20 ug/kg i.v.) in 11 normal men ( p < 0.005). This finding may indicate that SD enhances alpha-2 adrenergic receptor function or that the GH response to GH releasing factor in increased by SD.

Subtherapeutic erythropoietin and insulin-like growth factor-1 correct the anemia of chronic renal failure in the mouse.

Chronic renal failure (CRF) is associated with a hyporegenerative anemia, which is caused primarily by inadequate production of erythropoietin (EPO) by the diseased kidneys and is responsive to exogenous EPO administration. Little is known about compensatory mechanisms that might supervene in anemia with low levels of EPO. Multiple investigations in vitro suggest an important role for insulin-like growth factor-1 (IGF-1) as well as EPO in erythropoiesis. Recently, both EPO and IGF-1 in vitro have been found to stimulate erythroid colony forming units in the mouse. However, no studies have examined the effect of IGF-1, singly and in combination with EPO, in CRF in vivo. This study examined mice with surgically-induced renal failure of six weeks duration that were treated for three weeks with the combination of subtherapeutic doses of both EPO and IGF-1. The single administration of each cytokine caused no significant change in hemoglobin in all CRF mice. In marked contrast the combined administration of the two cytokines produced a striking rise in hemoglobin, resulting in anemia correction in the majority of animals. The response to the combination therapy was comparable to the maximal response obtained with a single EPO dose (10 U) in a dose-finding study. Although the data are limited to utilizing one dose of each cytokine and one preparation of IGF-1, the large increase in hemoglobin observed with the combination therapy indicates that these two cytokines work in concert to stimulate erythroid precursors in CRF. In addition, untreated CRF mice showed markedly increased serum levels of low molecular weight binding proteins for IGF-1, potentially reducing the bioavailability of IGF-1. These findings taken together suggest that the anemia of CRF may represent both an EPO and a functional IGF-1 deficient state.

Somatostatin pretreatment enhances growth hormone (GH) responsiveness to GH-releasing hormone: a potential new diagnostic approach to GH deficiency.

Despite the availability of numerous testing procedures to evaluate GH secretion in short children, there is still controversy about the most reliable test in the diagnosis of GH deficiency. We have recently demonstrated that in normal short children, priming with the long-acting somatostatin analog. SMS 201-995 (SMS), significantly potentiates their GH response to subsequent GHRH challenge. In the present study, we used the combined SMS + GHRH test in patients with GH deficiency to validate the hypothesis that this test would better discriminate between normal short children and those with truly diminished GH secretion. We studied 24 children classified into three groups according to their GH peak response to up to four conventional tests: 1) children with normal short stature and normal GH response (NSSA: GH peak > or = 10 micrograms/L, n = 6); 2) children with normal short stature with borderline GH response (NSSB: GH peak > or = 7 micrograms/L but < 10 micrograms/L, n = 4); and 3) GH-deficient children (GHD: GH peak < 7 micrograms/L, n = 14). Two study protocols were performed in all subjects: SMS (1 microgram/kg, sc) was randomly administered or omitted (control test) a 0800 h and GHRH (1 microgram/kg, iv) was given 5 h later. Plasma GH levels were measured every 30 min from 0800 h until 2 h after the GHRH injection. Pretreatment with SMS significantly augmented the GH peak response and the GH area under the GH concentration curve over 2 h after GHRH injection in the NSSA group, compared with control tests, but had no effect in the other two groups. While there was wide overlap of individual peak GH values to both the conventional tests and to the GHRH injection in the control test among the three groups of children, pretreatment with SMS resulted in complete discrimination between GHD and normal short children; the mean GH peak response to GHRH after SMS pretreatment was 8- to 9-fold lower in the GHD subjects (5.2 +/- 0.8 micrograms/L) compared with both the NSSA (44.0 +/- 14.3 micrograms/L; P < 0.01) and NSSB (42.9 +/- 5.0 micrograms/L; P < 0.01) groups and, more importantly, there was no overlap in the individual GH responses between GHD and normal short children. These results demonstrate that the combined SMS + GHRH test clearly discriminates normal short children from those with GHD. In view of its testing economy, safety, and accuracy, this combined test could become the test of choice to establish a diagnosis of GH deficiency in the slowly growing child.

Does growth-hormone supplementation affect adult height in Turner's syndrome?

BACKGROUND: By comparison with historical controls, the effect of treatment with growth hormone on adult height in Turner's syndrome was initially reported as uniformly and strongly positive. Because randomised controlled trials are not near completion, we report our experiences in an open study. METHODS: We examined adult height, projected and attained, in 31 patients (17 treated with subcutaneous recombinant human growth hormone, up to 15 mg a week, outside of a controlled trial and 14 untreated contemporaries). FINDINGS: Contingency table analysis of attained versus projected height showed significantly higher values in treated patients although only 4 of 17 had final heights of 5 cm or more over projection. Patients' and treatment variables (height, bone-age delay, oestrogen replacement) that interfere with adult height projection confounded the analysis of adult height data. INTERPRETATION: Girls with Turner's syndrome should be counselled cautiously about the expectation of a strongly positive effect of treatment on adult height. Completion of the randomised controlled trials to adult height is needed to establish the effect of growth-hormone supplementation on adult height in Turner's syndrome and the psychological effect of treatment.

The effect of Yohimbine, an alpha2 adrenergic receptor antagonist, on the growth hormone response to apomorphine in normal subjects.

Yohimbine HCl (16 mg po) administered 30 min before clonidine (CLON) (2 ug/kg infused over 10 min) (N = 5) or apomorphine HCl (Apo) (0.5 mg sc) (N = 10) antagonized the growth hormone (GH) response to CLON but had no effect on the GH response to Apo in normal men. This finding suggests that in humans, alpha2 adrenergic mechanisms do not modulate dopaminergic function, at least not in the hypothalamic-pituitary axis, and that the GH response to Apo is not mediated via an alpha2 adrenergic link.

Effect of follicular fluid supplementation on the in vitro development of human pre-embryos.

OBJECTIVE: To evaluate the value of supplementing a standard culture medium with 10% heat-inactivated mature follicular fluid (FF). DESIGN: Prospective randomized study evaluating the in vitro development of nontransferred, nonfrozen human pre-embryos in three culture conditions from day 3 to day 8 postfertilization. Preliminary evaluation by RIA and electrophoresis of factors responsible for these results. RESULTS: Ten percent mature FF supplementation of Inra Menezo (B2 medium) was associated with a significantly higher proportion of human pre-embryos reaching the morula (95% versus 72% with 10% maternal serum, P = 0.04) and the blastocyst stage (50% versus 11% with B2 alone, P = 0.02). The concentration of insulin-like growth factors I and II did not differ significantly between serum and mature FF-supplemented medium. Protein electrophoresis showed a difference of two bands corresponding to a molecular weight of 17,000 present in the serum and not in the FF-supplemented medium. CONCLUSION: Culture medium supplementation with 10% mature FF is associated with a significantly higher proportion of pre-embryos reaching the morula and blastocyst stage. The observed difference could be explained by the presence of a low molecular weight (17,000) embryotoxic factor contained in the serum-supplemented medium.

Use of Growth Hormone in children with short stature and normal Growth Hormone secretion: a growing problem.

The ethical, economic, psychologic, social, and growth attainment outcome issues related to the use of GH therapy in normal children with short stature are discussed. Although some short children accelerate their growth velocity with GH treatment, the limited available data do not suggest a significant benefit in final height attainment. An international survey of 99 normal short children treated with GH for at least 3 years reported a net improvement in mean height gain of <1 cm/year. Only in one-third was the result considered very good or good; 40% stated that there was no benefit. Thus, it seems unlikely that GH will dramatically increase final height in short children. On this basis, the use of GH for the treatment of the normal child with short stature outside of carefully controlled clinical trials cannot be recommended at present.

Pretreatment with somatostatin analog SMS 201-995 potentiates growth hormone (GH) responsiveness to GH-releasing factor in short children.

Previous studies in children have shown inconsistent, poorly reproducible GH responses to exogenous GH-releasing factor (GRF), with wide individual variability. In the present study, we tested the hypothesis that prior administration of the long-acting somatostatin analog, SMS 201-995 (SMS), will enhance GH responsiveness to a subsequent GRF challenge. Two study protocols were employed in 37 children with short stature [M = 31, F = 6, ages 11.8 +/- 1.6 yr (mean +/- SEM), height -2.25 +/- 0.55 SDS (SD scores)]. In both studies, each subject served as his/her own control. In the first study, which was designed to determine optimal SMS dose and regimen, SMS, in doses ranging from 0.8-2.2 micrograms/kg sc, was randomly administered or omitted at 0800 h after an overnight fast, and a GRF bolus (50 micrograms, iv) was given 4 h later. In the second study, we employed a protocol identical to study 1 except for the use of standard doses of SMS (1 microgram/kg, sc) and GRF (1 microgram/kg, iv) and an additional 1-h delay of the GRF injection. Plasma GH levels were measured every 20 min from 0800 h until 2 h after the GRF injection in both studies. In study 1 (n = 12; M = 10, F = 2), SMS significantly suppressed spontaneous GH secretion (expressed as the mean +/- SEM GH AUC during the 4-h SMS-GRF interval, AUC 1:2.2 +/- 0.4 vs. 6.2 +/- 0.9 micrograms/L.h; P < 0.001), GH responsiveness to GRF (GH AUC during the 2 h after the GRF injection, AUC 2: 41.5 +/- 7.8 vs. 85.0 +/- 13.5 micrograms/L.h; P < 0.001), and the GH peak response (17.4 +/- 3.1 vs. 36.0 +/- 6.2 micrograms/L; P < 0.001), compared to control tests. In contrast, in study 2 (n = 25; M = 21, F = 4), whereas spontaneous GH secretion was still suppressed during the 5-h SMS-GRF interval (AUC 1:3.8 +/- 0.4 vs. 7.4 +/- 1.1 micrograms/L.h; P < 0.001), both the GH peak response (56.7 +/- 5.5 vs. 30.5 +/- 3.0 micrograms/L; P < 0.0001) and the GH AUC (AUC 2: 103.7 +/- 10.3 vs. 77.5 +/- 6.8 micrograms/L.h; P < 0.05) after GRF administration were significantly augmented by pretreatment with SMS, compared to control tests. Taken together, these results indicate that a priming SMS dose of 1 microgram/kg has a significant permissive effect on GH responsiveness to exogenous GRF administered 5 h later.(ABSTRACT TRUNCATED AT 400 WORDS)

Detection of anti-pituitary autoantibodies by immunoblotting.

A new approach to the detection of anti-pituitary autoantibodies by immunoblotting is presented. This method distinguishes pituitary membrane fraction from cytosolic fraction autoantigens and characterizes them by their molecular weight. A 45 kDa pituitary specific membrane protein was identified as an autoantigen in one of 19 patients with idiopathic growth hormone deficiency and the empty sella syndrome. A 43 kDa membrane protein in pituitary and brain was identified as an autoantigen in one other patient with idiopathic growth hormone deficiency and in one of 14 patients with secondary growth hormone deficiency. These autoantibodies were not seen in any of 27 control subjects. Anti-pituitary autoantibodies can be demonstrated by immunoblotting at titres of up to 1/1000. We conclude that immunoblotting is a useful method for the detection of anti-pituitary autoantibodies.

Effects of synthetic growth hormone-releasing factor in women treated with gonadotrophin.

To evaluate the effects of synthetic growth hormone-releasing factor (GRF) in women with idiopathic infertility who were treated with human menopausal gonadotrophin (HMG), 13 women with this condition were randomly assigned to undergo treatment with HMG-GRF (500 micrograms twice daily) or HMG-placebo. Conception occurred in four of six women (14 cycles) who received HMG-GRF and in one of seven women (22 cycles) who received HMG-placebo. No difference was found in the amount of HMG and the duration of HMG required to induce ovulation between the two groups of patients. The overall serum growth hormone and insulin-like growth factor I concentrations were higher in the GRF than in the placebo group. No difference was found in serum oestradiol or inhibin concentrations between the two groups. Our results suggest that in women with idiopathic infertility, administration of GRF does not decrease the duration or the amount of HMG required to induce ovulation. However, it appears that in this small group concomitant treatment with GRF increases the pregnancy rates in women who are treated with HMG (4/14 cycles compared with 1/22 cycles).

Human embryos produce transforming growth factors alpha activity and insulin-like growth factors II.

OBJECTIVE: To assess whether growth factors are produced by early human embryos in culture. DESIGN: We studied various growth factors in the culture media of human embryos (n = 6) cultured from days 3 to 8 after fertilization. MAIN OUTCOME MEASURES: Four growth factors were measured: Insulin growth factors I and II (IGF-I and IGF-II), epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) activity. RESULTS: Nonconditioned INRA Menezo B2 (Biomerieux, S.A., Paris, France) culture medium contained significant levels of TGF alpha activity (5.2 ng/mL) and low levels of IGF-I (1.02 ng/mL) and IGF-II (2.8 ng/mL), whereas EGF was below detection of our assay. With human embryo, the culture media contained lower TGF alpha activity on days 3 and 4 after fertilization (2.5 ng/mL and 2.8 ng/mL, P less than 0.05). From days 5 to 8 after fertilization, a significant increase in TGF alpha activity and IGF-II was detected (TGF alpha activity: day 5: 3.7 ng/mL; day 6: 4.4 ng/mL; day 7: 6.4 ng/mL; day 8: 8.4 ng/mL) (IGF-II: day 5: 3.4 ng/mL; day 6: 3.1 ng/mL; day 7: 4.1 ng/mL; day 8: 4.2 ng/mL). Epidermal growth factor was undetectable, and IGF-I did not vary significantly. CONCLUSION: Transforming growth factor alpha activity and IGF-II are produced by human embryos in culture at a time when they could play a role in morula to blastocyst transformation.

Transforming growth factor-alpha and the ontogeny of epidermal growth factor receptors in rat kidney.

Epidermal growth factor exerts potent receptor-mediated mitogenic effects on a variety of target cells in vitro, but its importance in normal organ development is not yet fully understood. We report that the specific high-affinity receptors for EGF/TGF-Alpha increase dramatically in late gestational rat kidney (from 2.3% at 16 days gestation to 6.4% at term) and then fall toward basal adult levels (< 1% binding) during the first week of post-natal life. This post-natal fall-off in EGF binding corresponds temporally to the period when replication of rat kidney DNA begins to slow (4-7 days of post-natal life). EGF mRNA is not detectable in rat kidney by Northern analysis until the second week of post-natal life, but high levels of transforming growth factor-alpha are demonstrable by specific radioimmunoassay in extracts of fetal kidney (52.2 +/- 8.2 pmoles/gram kidney) and amniotic fluid (4.49 +/- 0.75 pmoles/ml). We speculate that induction of EGF-receptors in fetal rat kidney may confer responsiveness to local transforming growth factor-alpha and dictate the rate of hyperplastic renal growth in the perinatal period.

Expression of transforming growth factor-alpha and epidermal growth factor receptor in human fetal kidneys.

Beginning at the fifth week of fetal life, successive generations of individual nephrons are induced by contact between metanephric mesenchyme and ureteric bud. Following phenotypic transformation, cells of each primitive renal vesicle undergo a phase of rapid cell division. In order to identify genes which might regulate nephron development in man, we screened adult and fetal kidney RNA for expression of a panel of growth-related genes. Among the genes which were expressed at higher levels in fetal kidney was the epidermal growth factor (EGF) receptor. There is controversy as to the most likely physiologic EGF receptor ligand in fetal kidney; we were able to identify a transcript for transforming growth factor-alpha (TGF-alpha) but not EGF on Northern blots of fetal kidney RNA. Since the abundance of TGF-alpha mRNA is low, we confirmed its presence by polymerase chain reaction amplification. Using specific radioimmunoassays, we also provide direct evidence for TGF-alpha but not EGF peptide in extracts of fetal kidney and mid-gestational amniotic fluid. We suggest that TGF-alpha/EGF receptor interactions may serve an important function in development of human fetal kidney.