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Biomedical subjects

R Rappaport

Publications and source records attributed to R Rappaport.

At least 19 recordsLinked to original sources

[Determination of growth hormone binding protein in a normal population and in subjects with short stature due to growth hormone resistance].

With the procedure which uses gel-filtration and high pressure liquid chromatography (HPLC) the authors measured the GH-binding proteins in 96 healthy subjects aged 6 months to 40 years. In the blood 45% of the GH is bound to the BP. The diagnosis was confirmed by our method in 13 patients with Laron type dwarfism and in four patients the GH receptor defect had been proved. The parents, the brothers and sisters showed significantly lower GH-BP II (principal GH-BP) levels. Possible regulation of GH-binding proteins in human plasma was examined. Eight children with isolated GH deficiency had a very low level of plasma GH binding activity (mean +/- SEM) (10.2 +/- 1.1% of radioactivity). Under GH treatment the hormone binding to high affinity BP (GH-BP II) increased in every patient to reach the mean value of 18.5 +/- 1.4%. This increase was related to a higher binding capacity without any significant change in the binding affinity. In nine boys with pubertal delay, the GH specific binding to peak II-BP (GH-BP II) was found to be normal (30.6 +/- 3.7%); it decreased significantly following testosterone treatment. In four boys with precocious puberty, the specific GH binding to peak II BP was low (16.6 +/- 1.1%). It increased significantly to 21.6 +/- 1.1% of radioactivity after treatment with LH-RH analogue. GH and testosterone have an opposite role in the regulation of the high affinity GH-BP.

Adolescent

Predictive factors for the effect of gonadotrophin releasing hormone analogue therapy on the height of girls with idiopathic central precocious puberty.

The factors influencing the final height of central precocious puberty patients treated with gonadotrophin releasing hormone (GnRH) analogues remain a critical issue. This study compares the predicted final height before and after GnRH analogue therapy to identify predictive factors for final height. Fourteen girls with idiopathic central precocious puberty were treated with a GnRH analogue. All had an active non-regressive form before therapy, full and permanent suppression of oestrogenic activity during therapy (duration greater than 2 years, 3.1 +/- 0.3 years, mean +/- SEM), and the pubertal pituitary-ovarian axis had normalized in all of them 1 year after the cessation of therapy. The mean predicted final height increased from 152 +/- 1.8 cm before therapy to 162.2 +/- 1.2 cm (P less than 0.01) at the last evaluation performed 4.5 +/- 0.3 years after the onset of therapy. The mean gain in predicted final height between the onset of therapy and the last evaluation was 10.2 +/- 1.1 cm. It was correlated with the following data recorded at the onset of therapy: bone age advance over chronological age (r = 0.66, P less than 0.02), predicted final height at the onset of therapy (r = -0.76, P less than 0.001), and the difference between the target height and the predicted height at onset of therapy (r = 0.76, P less than 0.001). We conclude that GnRH analogue therapy is more likely to improve final height prognosis in girls who initially present with a markedly advanced bone age and a great difference between their target and predicted heights. Both these parameters reflect the severity of the disease at diagnosis.

Body Height

Preservation of ovarian function by ovarian transposition performed before pelvic irradiation during childhood.

Ovarian transposition in adults has been shown to protect ovarian function in about 60% of cases by reducing ovarian exposure to less than 4 to 7 Gy. We therefore evaluated the effect of ovarian transposition during childhood or adolescence. Eighteen girls had ovarian transposition performed at a mean (+/- SEM) age of 9.4 +/- 1.2 years (range, 1.2 to 16 years). Twelve were prepubertal and six had menstruated at the time of ovarian transposition. The initial abnormalities were Hodgkin disease (5 cases), iliac Ewing sarcoma (3), medulloblastoma (2), ovarian seminoma (1), and vaginal or uterine tumor (7). The irradiation was external in 11 cases and local by vaginal curietherapy in 7 cases. Fifteen girls received chemotherapy. The ovarian transposition was bilateral in 15 patients and unilateral in 3 cases; in the latter the other ovary had been destroyed by the tumor or by abdominal irradiation. Ovaries were placed just below the iliac crest (15 cases) or posterolateral to the uterus (3); thus, the calculated ovarian radiation dose was up to 9.5 Gy. At the time of evaluation (8.6 +/- 0.9 years after ovarian transposition), 16 girls had menstruated and 2 remained amenorrheic because of major lesions of the vagina and uterus caused by the vaginal curietherapy. Basal plasma gonadotropin values were normal. Ovulation was documented in seven cases. Two pregnancies occurred. Complications of ovarian transposition were present in four patients: intestinal occlusion, dyspareunia, functional ovarian cysts, and pelvic adhesions with tubal obstruction. We conclude that ovarian transposition, performed before abdominopelvic irradiation during childhood, can preserve ovarian function. Longer follow-up is required to assess the risk of ovarian dystrophy because of vascular lesions or chemotherapy.

Adolescent

Effect of growth hormone on the low level of growth hormone binding protein in idiopathic short stature.

OBJECTIVE: Growth hormone receptor status was assessed in children with idiopathic short stature by evaluating plasma growth hormone-binding protein before and under GH therapy. DESIGN: Among 22 children presenting idiopathic short stature, 15 were randomly selected to be treated with GH (1.2 IU/kg/week); they were studied before and under GH therapy. Untreated patients served as a control group for age and GH effect. PATIENTS: Twenty-two prepubertal children, aged 5-11 years, were studied. They presented growth retardation of -2.8 +/- 0.1 SDS (mean +/- SEM). All had normal GH secretion and their mean IGF-I plasma level was normal. MEASUREMENT: Growth hormone-binding protein was measured using high pressure liquid chromatography gel filtration. The specific binding of 125I-hGH to the growth hormone-binding protein was expressed as a percentage of the total radioactivity. RESULTS: Specific binding of 125I-hGH to the high affinity growth hormone-binding protein was low with a mean +/- SEM value of 11.1 +/- 0.9% of radioactivity. In the treated group, growth hormone-binding protein increased significantly after 3 months of treatment; it reached 21.1 +/- 1.0% of radioactivity (mean +/- SEM) in the eight children who have been treated for 18 months. In the seven untreated children, the growth hormone-binding protein value increased to 16.2 +/- 1.1% after 18 months; this value is significantly lower than that found in the GH-treated children, demonstrating that the GH effect is greater than the age-related increase in the growth hormone-binding protein. A positive correlation was found between IGF-I plasma levels and growth hormone-binding protein and also between growth velocity and growth hormone-binding protein. CONCLUSIONS: The low growth hormone-binding protein and the response to high doses of GH suggest partial GH resistance at the receptor level, in this group of children with idiopathic short stature.

Carrier Proteins

Effect of social class and nutrient intake on height and plasma insulin-like growth factor in Andean Equadorian children.

The purpose of this study was to assess the validity of insulin-like growth factor (IGFI) determination as an index of nutritional status and growth in Equadorian schoolboys. Plasma IGFI was measured in 144 healthy boys, 9 years old, who were classified by their social class in four groups: 1 (n = 29); 2 (n = 49); 3 (n = 28); 4 (n = 8). Children in groups 1 and 2, of the lower socio-economic class, had significantly reduced caloric and protein intakes compared to children in groups 3 and 4 (P less than 0.01). Mean heights were significantly lower in groups 1 and 2 (P less than 0.001 and less than 0.05, respectively). The mean plasma IGFI in group 1 was 561 +/- 64 mU/ml and significantly lower than that in groups 2-4 (872 +/- 75, 986 +/- 94, and 1238 +/- 190 mU/ml in groups 2, 3 and 4, respectively) (P less than 0.01). The effect of caloric and nitrogen supplementation was studied in 36 children taken from groups 1 and 2 combined, and divided into three subgroups; they were given (1) an animal protein supplement of 18 g/day with 860 kcal/day (n = 12), (2) a vegetable protein supplement of 17.8 g/day based on a traditional Andean food with 862 kcal/day (n = 12), and (3) a placebo (n = 12). The IGFI levels increased significantly after 7 and 14 days in both subgroups 1 and 2. These results demonstrate that plasma IGFI reflects the nutritional status and responds to a short-term diet supplementation. It may provide a reliable means of assessing the effect of nutritional programs intended to improve the growth of children in underdeveloped countries.

Body Height

The short-term effect of testosterone on growth in boys on hemodialysis.

In view of a possible resistance to hormones as a cause of growth failure in renal insufficient children, a short-term study was performed to assess the effect of low-dose testosterone administration in boys with end-stage renal failure. Eight boys with a mean age of 11.4 +/- 1.2 years and a mean height deviation of -3.9 SD according to French standards received 50 mg/m2/day of a testosterone or placebo gel in a double-blind crossover fashion, each for a period of four weeks. Growth velocity was assessed by knemometry. The mean plasma testosterone levels rose from 0.16 +/- 0.06 ng/ml to 1.98 +/- 0.35 ng/ml during the testosterone treatment (p less than 0.01), whereas it remained low during the placebo treatment: 0.23 +/- 0.09 ng/ml versus 0.19 +/- 0.06 ng/ml before. The mean growth velocity rose from 0.27 +/- 0.07 mm/week during the control period to 0.50 +/- 0.03 mm/week during the testosterone treatment (p less than 0.05). Two groups of boys could be distinguished: the four boys of the first group whose initial growth velocity was below the mean growth velocity of a healthy control group, showed a significant improvements during the testosterone treatment (p less than 0.01). The growth velocity of the four boys of the second group whose initial growth velocity was normal did not improve during the testosterone treatment. These facts suggest that low dose testosterone can stimulate short-term growth of boys on regular hemodialysis when the basal growth velocity is low.

Administration, Cutaneous

Plasma growth hormone-binding activity is low in uraemic children.

Plasma growth hormone-binding protein (GH-BP) activity was evaluated in two groups of prepubertal children with chronic renal failure (CRF) who had been treated with recombinant human GH (rhGH). Group 1 consisted of eight children (mean chronological age 10.8 years) with advanced renal failure; group 2 consisted of nine children (mean chronological age 6 years) presenting with end-stage renal disease, who were on dialysis. Before treatment the specific binding of (125I)hGH to high-affinity GH-BP was low in the two groups (group 1, 17.3 +/- 1.6% of radioactivity; group 2, 14.2 +/- 1.4%) compared with the mean value obtained in normal prepubertal children (24.8 +/- 1.7%). No significant changes in GH-BP activity were found during the 1st year of GH therapy, although growth velocity and plasma levels of insulin-like growth factor-I increased significantly in both groups. The low GH-binding activity found in children with CRF supports the state of GH resistance. The reason for the absence of a GH-BP response to GH therapy has to be clarified.

Carrier Proteins

Polygraphic sleep patterns and growth hormone secretion in children after cranial irradiation.

The effects of radiotherapy on subsequent growth hormone (GH) secretion and sleep organization was studied by simultaneous evaluation of spontaneous sleep-related GH secretion (SSRGHS), arginine-insulin tolerance test (AITT) and polygraphic sleep recording in a follow up of 19 children who underwent surgical removal of an intracranial tumour and cranial radiotherapy 1-7 years previously. Electrophysiological patterns of sleep phases, the amount and distribution of sleep stages were normal, suggesting that the procedure utilized should not entail modifications of SSRGHS per se. Long-term after radiotherapy SSRGHS and AITT GH responses were lower than those of the medium-term group. The lack of correlation between SSRGHS and AITT GH secretion suggests that SSRGHS and AITT measure different aspects of GH secretion. The highest value of GH plasma level (peak) corresponded to slow wave sleep, mainly during the first non-rapid eye movement-rapid eye movement (NREM-REM) cycle, in practically all the patients. Although the SSRGHS synchronization with SWS of the first NREM-REM cycle was preserved, no sleep measure was correlated with the SSRGHS. The usefulness of polygraphic monitoring of sleep patterns was confirmed.

Arginine

Height of normal pituitary gland as a function of age evaluated by magnetic resonance imaging in children.

MR anatomy of hypothalamo-hypophyseal axis is well established. However data about pituitary gland height (PGH) in children are sparse. A retrospective study was therefore performed in 60 children (30 boys and 30 girls) aged from 8 days to 21 years. All these children had MR for various neurological diseases. Patients with hypothalamo-hypophyseal disease and intracranial hypertension were excluded. The PGH was measured on a strict midline sagittal T1 weighted scan 3 to 7 mm thick. A positive linear correlation was found in children aged from 1 year to puberty followed by a plateau. In the first year of life a negative linear correlation was found. A positive linear correlation was found between PGH and statural height as well.

Adolescent

Age-dependent responsiveness of rabbit and human cartilage cells to sex steroids in vitro.

Rabbit epiphyseal cartilage tissue has been shown to convert testosterone (T) to dihydrotestosterone (DHT). In this report, the metabolic conversion of T into DHT is shown to be age-dependent, being most active in cartilage from animal at the age of gonadal maturation. Human cartilage from newborn and prepubertal children is also shown to convert T into DHT and--to a lesser extent--to estradiol. Low concentrations of DHT and 17 beta-estradiol (E2) (10(-11)-10(-9) M) were also shown to stimulate in vitro cartilage cells from boys and girls respectively. As previously shown for cultured rabbit chondrocytes, the stimulating effects of both hormones on human chondrocytes was age-dependent. Cartilage cells derived from children up to one year old did not respond, while cells from boys and girls in the early phase of puberty responded best. These data indicate that human cartilage tissue in vivo, contains both 5 alpha-reductase and aromatase activities during post-natal skeletal growth. Androgens may act on cartilage after their metabolic conversion to estrogens. The mechanism of age-dependency of both cartilage androgen enzymatic activities and chondrocyte responsiveness to sex steroids in vitro remains to be explained.

Age Factors

Comparative study of biosynthetic human growth hormone immunogenicity in growth hormone deficient children.

The immunogenicities of six recombinant human growth hormone (rhGH) preparations, from KABI (A rhGH191 and B rhGH192), Eli Lilly (C), Nordisk (D), Sanofi (E) and Serono (F), used to treat 260 GH-deficient children, have been compared using a common specific and sensitive procedure for antibody determination. For this purpose we developed two immunoassays: a competitive liquid radioimmunoassay using 125I-rhGH, and an immunometric solid enzymoimmunoassay in which the rhGHs were immobilized. Blood samples were collected from the GH-deficient children before treatment and after 3, 6, 9, 12, 18 and 24 months of therapy. Human GH antibodies were detected in children treated with 3 of the 6 rhGH preparations. Seven percent of the patients treated with hormone A, 14% with hormone B and 22% with hormone C formed antibodies against the respective rhGH. Differences in capacity and affinity of the hGH antibodies were observed between these anti-GH-positive groups. They could be divided into 2 groups according to their immunopotency. One group (7, 14 and 6% of the patients treated with hormones A, B and C, respectively) developed anti-hGH antibodies with very low binding capacities (30-100 fmol/ml). The other group (16% of the patients treated with hormone C) developed IgG-type antibodies to hGH with higher binding capacities (200-1,200 fmol/ml) and a measurable binding affinity (Ka = 10(8) M-1). These hGH antibodies partially inhibited the binding of labeled GH to its specific liver membrane receptor. However, because of their low titer, they did not inhibit growth in the treated children.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent

Idiopathic central precocious puberty in girls as a model of the effect of plasma estradiol level on growth, skeletal maturation and plasma insulin-like growth factor I.

Girls suffering from idiopathic central precocious puberty (CPP) may have different levels of estrogenic activity. This study was performed to evaluate the relationship between the estrogenic activity and the hypothalamopituitary activation and the effect of various plasma estradiol (E2) levels on growth, skeletal maturation and plasma insulin-like growth factor I (IGF-I). Fifty-eight girls with CPP were divided into 2 groups: group I with E2 less than 25 pg/ml (13 +/- 1 pg/ml, mean +/- SEM, n = 26) and group II with E2 greater than or equal to 25 pg/ml (52 +/- 3 pg/ml, n = 32). The mean ages at onset and at evaluation were lower in group I (5.9 +/- 0.4 and 6.8 +/- 0.4 years) than in group II (6.8 +/- 0.3 and 8.1 +/- 0.2 years, p less than 0.01), but the durations since onset (greater than 0.5 and less than 2 years) in the two groups were similar. The mean peak luteinizing hormone/follicle-stimulating hormone (LH/FSH) ratios were lower in group I (0.8 +/- 0.2) than in group II (1.7 +/- 0.2, p less than 0.001) and correlated with E2 (r = 0.41, p less than 0.01). The mean height gains during the year preceding the initial evaluation were similar in the two groups (8.7 +/- 0.5 vs. 9.2 +/- 0.4 cm). They were independent of the plasma E2 level. Conversely, the mean plasma IGF-I values were lower in group I (2.4 +/- 0.3 U/ml) than in group II (4.2 +/- 0.6 U/ml, p less than 0.01) and correlated with E2 (r = 0.52, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Development

Recurrent nonsense mutations in the growth hormone receptor from patients with Laron dwarfism.

In addition to its classical effects on growth, growth hormone (GH) has been shown to have a number of other actions, all of which are initiated by an interaction with specific high affinity receptors present in a variety of tissues. Purification of a rabbit liver protein via its ability to bind GH has allowed the isolation of a cDNA encoding a putative human growth hormone receptor that belongs to a new class of transmembrane receptors. We have previously shown that this putative growth hormone receptor gene is genetically linked to Laron dwarfism, a rare autosomal recessive syndrome caused by target resistance to GH. Nevertheless, the inability to express the corresponding full-length coding sequence and the lack of a test for growth-promoting function have hampered a direct confirmation of its role in growth. We have now identified three nonsense mutations within this growth hormone receptor gene, lying at positions corresponding to the amino terminal extremity and causing a truncation of the molecule, thereby deleting a large portion of both the GH binding domain and the full transmembrane and intracellular domains. Three independent patients with Laron dwarfism born of consanguineous parents were homozygous for these defects. Two defects were identical and consisted of a CG to TG transition. Not only do these results confirm the growth-promoting activity of this receptor but they also suggest that CpG doublets may represent hot spots for mutations in the growth hormone receptor gene that are responsible for hereditary dwarfism.

Dwarfism

Human plasma growth hormone (GH)-binding proteins are regulated by GH and testosterone.

Possible regulation of GH-binding proteins (GH-BPs) in human plasma was examined. Eight children with isolated GH deficiency had a very low level of plasma GH-binding activity (10.2 +/- 1.1% of radioactivity). Under GH treatment the hormone binding to the high affinity BP (peak II-BP) increased in every patient to reach the mean value of 18.5 +/- 1.4%. In one patient, Scatchard plot analysis indicated that this increase was related to a higher binding capacity without any significant change in the binding affinity. A positive correlation existed between the GH-binding activity and insulin-like growth factor-I plasma levels. In nine boys with pubertal delay, the GH-specific binding to peak II-BP was normal (30.6 +/- 3.7% of radioactivity); it decreased significantly after testosterone treatment. In four boys with precocious puberty, the specific GH binding to peak II-BP was low (16.6 +/- 1.1%). It increased significantly to 21.6 +/- 1.1% of radioactivity after treatment with a LHRH analog. A negative correlation existed between plasma testosterone levels and GH binding to peak II-BP in boys presenting pubertal delay or precocious puberty. The high affinity GH-BP is regulated, and among the factors that play a role in this regulation, GH and testosterone have opposite effects.

Adolescent