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Biomedical subjects

Z Laron

Publications and source records attributed to Z Laron.

At least 91 records · Page 5Linked to original sources

Renal function in Laron syndrome patients treated by insulin-like growth factor-I.

Eight children with Laron syndrome (5 males, 3 females) aged 3-14.5 years received daily subcutaneous injections of 150 micrograms/kg recombinant insulin-like growth factor-I (IGF-I) for 5 months. The children were examined weekly for the 1st month and then once monthly. At each visit, overnight fasting blood was drawn for serum IGF-I and blood chemistry measurements and a 24-h urine collection was performed for the determination of calcium, phosphorus, creatinine and nitrogen. The main effects related to kidney function were: an initial weight gain with a mild transitory reduction in the urinary volume, an increase in serum electrolyte concentrations and a decrease in urinary electrolyte excretion. The lower than normal mean (+/- SEM) basal creatinine clearance (76.7 +/- 15.8 ml/min per 1.73 m2) increased towards the normal range during treatment to 124.9 +/- 13 ml/min per 1.73 m2, with a mean increment of 73.4 +/- 28% (P < 0.02) from basal values after 2 months of treatment, without changes in the serum creatinine. Initially an increase in blood urea nitrogen was observed together with a reduction in urinary nitrogen excretion. During the IGF-I therapy the urinary calcium excretion increased from 0.7 +/- 0.2 nmol/day to 1.5 +/- 0.3 nmol/day and the tubular reabsorption of phosphate increased from 1.24 +/- 0.06 to more than 1.38 +/- 0.04 nmol/l (P < 0.002), resulting in a significant increase in serum phosphate levels from 1.51 +/- 0.06 to more than 1.63 +/- 0.04 nmol/l (P < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Growth hormone (GH) stimulates insulin-like growth factor-I (IGF-I) and IGF-binding protein (IGFBP)-2 gene expression in spleens of juvenile rats.

Growth and development of the spleen involves the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis. To evaluate the molecular mechanism of these effects we studied the effect of hypophysectomy (Hx) and GH replacement therapy on the expression of IGF-I, the IGF-I receptor and IGF-binding protein-2 (IGFBP-2) in juvenile rats. Hx resulted in a 30% reduction in body weight. GH replacement therapy for seven days partially prevented these effects. IGF-I mRNA levels were reduced 30% by Hx, IGFBP-2 mRNA levels fell 50% whereas IGF-I receptor mRNA levels were unaffected. GH therapy prevented the reduction in IGF-I and IGFBP-2 mRNA levels. These results suggest that the GH effect on splenic growth and development is via local (paracrine) IGF-I expression, in addition to any effect by circulating (endocrine) IGF-I.

Animals↗

IGF-I treatment of adult patients with Laron syndrome: preliminary results.

OBJECTIVE: Laron syndrome is a genetic disease due to a defect in the GH receptor or in the post-receptor mechanism which leads to an inability to generate IGF-I. Biosynthetic IGF-I treatment given to dwarfed children with this syndrome, produced a significant acceleration of growth velocity and reduction in obesity. In view of the known metabolic disturbances in untreated adult patients, the present clinical trial was performed to define the usefulness of IGF-I treatment in LS adults. PATIENTS AND DESIGN: Five patients (1 male, 4 females) aged 28-40 years were treated during 9 months by daily administration of IGF-I (120 micrograms/kg), and followed for 6 months after its discontinuation. METHODS: At each visit, a complete physical examination was performed and blood was drawn for biochemical and hormone determinations. Twenty-four-hour urinary samples were collected at various intervals during treatment. Bone densitometry was performed before and after 6-9 months of therapy. RESULTS: The main findings were a reduction in subscapular skinfold thickness (from 27.5 +/- 1.4 (mean +/- SEM) to 19.5 +/- 1.0 mm; P < 0.002), a decrease in total cholesterol (from 6.78 +/- 0.28 (mean +/- SEM) to 5.80 +/- 0.36 mmol/l) and in LDL cholesterol (from 4.86 +/- 0.23 to 3.76 +/- 0.35 mmol/l), an increase in creatinine clearance (from 71.2 +/- 8.4 to 86.8 +/- 4.3 ml/min/1.73 m2, P < 0.04), an increase in phosphate reabsorption (from 0.89 +/- 0.06 to 1.14 +/- 0.06 mmol%; P < 0.02) leading to an increase in serum phosphate (from 1.08 +/- 0.06 to 1.27 +/- 0.03 mmol/l; P < 0.03), a rise in alkaline phosphatase (from 80.8 +/- 5.0 to 100.7 +/- 7.0 U/l) and in procollagen I-PICP (from 44.2 +/- 4.0 to 171.0 +/- 19.2 micrograms/l; P < 0.0001) and in procollagen III-PIIINP (from 2.68 +/- 0.45 to 10.10 +/- 1.4 micrograms/l; P < 0.005). There was a transient retention of water, sodium and chloride. Pretreatment serum IGFBP-3 levels were low, but increased progressively during treatment. This permitted a reduction in the IGF-I dose. There were no adverse effects other than pain and slight erythema at the injection site during the first weeks of treatment. All the anthropometric and metabolic changes reversed upon discontinuation of IGF-I. CONCLUSIONS: IGF-I treatment is beneficial in adults, as well as in children, with resistance to GH.

Adult↗

Comparative effects of GH, IGF-I and insulin on serum sex hormone binding globulin.

OBJECTIVE: The serum level of sex hormone binding globulin (SHBG) changes inversely with that of both insulin and insulin-like growth factor (IGF-I), during several nutritional conditions, as well as in response to GH treatment. However, with exogenous IGF-I administration, endogenous IGF-I increases, while insulin decreases. In order to study the separate roles of these hormones in controlling SHBG metabolism, we compared SHBG levels in patients treated with IGF-I and GH. DESIGN AND PATIENTS: Serum levels of IGF-I, insulin and SHBG were measured before and during the treatment of patients with IGF-I or GH. Blood samples were drawn in the fasting state, prior to and during therapy, 24 hours after drug administration. Sixteen children and adults with Laron syndrome (LS) received daily s.c. injections of IGF-I (120-150 micrograms/kg) for up to 5 months. Three adults with isolated GH deficiency (IGHD) received daily s.c. injections of GH (0.03-0.06 U/kg) for 16 months. Two groups of nine prepubertal children with constitutional short stature (CSS) received GH (0.1 U/kg/day) for 3 months. MEASUREMENTS: Serum levels of insulin and acid extractable IGF-I were determined by RIA, and that of SHBG by IRMA. RESULTS: Basal insulin and SHBG levels were within normal range in the LS, IGHD and CSS patients. IGF-I levels were low in LS and IGHD patients, and normal in the CSS children. The mean peak response to chronic therapy was as follows: in LS patients, IGF-I administration decreased insulin levels to 62%, and increased SHBG levels by 64% above basal values. Chronic GH therapy in IGHD caused a marked rise in both IGF-I levels (473%), and insulin levels (96%), and a gradual decline of SHBG to 75% of the basal concentration. In GH treated CSS patients, serum IGF-I peaked at 80% and insulin levels at 102% above the respective basal levels, while SHBG decreased to 83% after 5 days of treatment. CONCLUSION: The results obtained in Laron syndrome, isolated GH deficiency and constitutional short stature patients treated with IGF-I or GH, indicate that serum insulin had consistently an inverse relation with the levels of circulating SHBG. No relation was found between IGF-I and SHBG levels.

Adult↗

Growth hormone releasing activity by intranasal administration of a synthetic hexapeptide (hexarelin).

OBJECTIVE: Hexarelin is a new synthetic growth hormone releasing peptide. We have tested the efficacy of intranasal (i.n.) administration of hexarelin to stimulate plasma GH and have compared this to the intravenous (i.v.) administration of the peptide. PATIENTS: Ten children with familial short stature (FSS) aged 5.5-15.5 years and two known GH deficient patients aged 24 and 28 years without GH treatment. METHODS: All 12 subjects were submitted to i.v. (1 microgram/kg) and i.n. (20 micrograms/kg) hexarelin tests with a one-week interval between tests. Blood samples for GH, TSH, fT4 and T3 were obtained at 0, 15, 30, 60, 90 and 120 minutes. The hormone determinations were made by standard radio-immunoassays (RIA). RESULTS: Both the i.n. and i.v. administration of hexarelin induced a large GH response, the mean (+/- SD) being 72.2 +/- 35.5 mU/l for the i.n. test and 79.6 +/- 53.0 mU/l for the i.v. test. The peak GH in the i.v. test occurred at 15-30 minutes and in the i.n. test between 30 and 60 minutes. The GH deficient patients showed no GH response in either test. Plasma TSH decreased in the FSS children from a mean (+/- SD) of 1.0 +/- 0.26 to 0.64 +/- 0.2 mU/l (P < 0.005) during the i.n. test and from 1.0 +/- 0.3 to 0.7 +/- 0.3 mU/l (P < 0.05) during the i.v. test. In the isolated GH deficient patient, plasma TSH decreased from 1.06 +/- 0.38 mU/l to 0.86 +/- 0.17 during the i.v. test and from 1.60 +/- 0.01 to 1.11 +/- 0.06 mU/l during the i.n. test. There were no significant changes in plasma fT4 or T3 in any of the tests. CONCLUSIONS: The synthetic hexapeptide hexarelin is a potent pituitary GH stimulator when administered intranasally. The GH response was similar to that observed after intravenous hexarelin. Simultaneously, there was a significant decrease in plasma TSH but the concentrations remained in the normal range. These findings appear to be of theoretical and practical relevance to the investigation and management of short children.

Administration, Intranasal↗

Genetic predisposition to hypertension (as detected by Na+/Li+ countertransport) and risk of diabetic nephropathy in childhood diabetes.

In order to evaluate whether insulin-dependent diabetes mellitus patients with incipient nephropathy have an overactivity of erythrocyte sodium-lithium countertransport (Na+/Li+ CT), 82 diabetic children and 38 healthy age-matched control subjects and their parents and grandparents were studied. The children were divided into two groups according to the presence of persistent microalbuminuria (MA). Diabetic children with MA had Na+/Li+ CT activity higher than normoalbuminuric diabetics and healthy controls. The parents and grandparents of microalbuminuric patients showed higher Na+/Li+ CT than parents and grandparents of normoalbuminuric diabetics and of the controls. This study demonstrates that predisposition to hypertension, as indicated by increased Na+/Li+ CT activity in erythrocytes, is more frequently detectable in patients with persistent microalbuminuria than in diabetics without persistent microalbuminuria or in healthy controls. Overactivity of Na+/Li+ CT is present also in parents and grandparents of diabetic children with MA. This study suggests that genetic predisposition to hypertension is more frequent in patients at risk of developing diabetic nephropathy, as well as in their parents and grandparents.

Adolescent↗

Receptor mutations and haplotypes in growth hormone receptor deficiency: a global survey and identification of the Ecuadorean E180splice mutation in an oriental Jewish patient.

Eight different mutations were detected in the growth hormone (GH) receptor gene of patients with inherited GH receptor deficiency (GHRD; Laron syndrome) from five continents. All the mutations are located in the extracellular domain of the receptor and are predicted to cause gross structural abnormalities and non-functional receptor molecules. They include three nucleotide changes in the coding region causing translational stop signals, including the newly identified E183X mutation; two nucleotide changes in introns that affect splice junctions; two dinucleotide deletions that result in stop codons downstream; and one single nucleotide change that activates a donor splice site within an exon and results in a transcript missing 24 nucleotides. This latter mutation (E180splice) was first identified in a cohort of patients with GHRD from southern Ecuador. Based on the fact that the E180splice mutation generates a new cleavage site for the restriction enzyme MnlI, a simple diagnostic test has been developed that can be carried out on dried blood spots collected on filter paper. A total of 55 affected individuals from Ecuador has been found to be homozygous for this mutation. Asymptomatic carriers can also be detected, and 104 of 150 individuals screened were found to be carriers. Using this test, the E180splice mutation has recently been detected in one of two oriental Jewish patients from Israel.

Base Sequence↗

Laron syndrome: clinical features, molecular pathology and treatment.

Primary growth hormone (GH) insensitivity (Laron syndrome) is a hereditary disease due to polymorphic defects in the GH receptor, or in the postreceptor mechanisms, leading to an inability to generate IGF-1. The clinical features and biochemical profiles are indistinguishable from isolated GH deficiency. A diagnostic feature is the lack of rise of serum IGF-1 in response to GH. In most patients growth hormone binding protein is low. Treatment of children with Laron syndrome by biosynthetic IGF-1 accelerates linear growth velocity and head circumference, reduces body fat, and stimulates kidney function.

Adolescent↗

Impact of the Gulf War on the anxiety, cortisol, and growth hormone levels of Israeli civilians.

OBJECTIVE: The authors investigated the impact of continuous and repeated stress on Israeli civilians exposed to missile attacks during the Gulf War. METHOD: Study 1 included 26 healthy volunteers aged 28-59 years. Their scores on the Hamilton Anxiety Rating Scale and levels of plasma cortisol and growth hormone (GH) were evaluated before, during, and after the war. Study 2 included 13 healthy volunteers aged 25-59 years. Their scores on the state portion of the State-Trait Anxiety Inventory and levels of cortisol and GH were measured three times daily (8:00 a.m., noon, and 6:00 p.m.) at two time points (during and after the war). RESULTS: Anxiety levels of civilians exposed to the threat of war and later to actual missile attacks were significantly higher before and during the war than afterward. Anxiety during the war reached a peak in the evening. The increase in anxiety was not accompanied by any change from basal morning cortisol and GH levels or by diurnal variations in these hormones. CONCLUSIONS: Anxiety levels during the war were similar to those 1 day before its onset, which can be explained by the nature of coping processes. During the war, anxiety levels were highest in the evening, reflecting the war routine (missile attacks occurred mostly at night). The unaltered hormone levels and their normal diurnal variations despite the subjects' persistent anxiety were probably due to adaptation of the hypothalamic-pituitary-adrenal and hypothalamic-somatotropin axes to continuous stress.

Adult↗

Serum growth hormone-binding protein (GHBP) activity is decreased by administration of insulin-like growth factor I in three Laron syndrome siblings with normal GHBP.

Three Laron Syndrome (LS) siblings with a post growth hormone (GH) receptor defect for insulin-like growth factor-I (IGF-I) synthesis were found to have serum GH-binding protein (GHBP) levels normal for age. Treatment with recombinant IGF-I (150 micrograms/kg/day) decreased serum GHBP activity to 62% of the basal value (P < 0.001) in two of the sibs in 1 week and in the third sib after 3 months of therapy. Scatchard analysis of the binding of [125I]human GH (hGH) to GHBP in patients' sera before and during therapy revealed affinity constants Ka = 1.55-1.80 x 10(9) M-1, similar to that of sera from healthy subjects. Variations in binding are due to changes in the binding capacity. IGF-I may be a regulatory factor for serum GHBP activity in man.

Carrier Proteins↗

Psychological aspects of developmental endocrinopathies in adolescence.

Ninety-six adolescents referred to a pediatric endocrinology clinic were divided into eight groups according to degree of sexual maturity and height. Each adolescent was assessed by a psychiatric interview, a self-concept questionnaire, a human figure drawing test and a cognitive screening battery. The results showed a definite deleterious effect of growth retardation, but not sexual maturity, on self-concept. Sex of the adolescent did not affect the results. Cognitively there was no difference between groups. The psychological impact of short stature should be taken into consideration in the decision to utilize pharmacological or delay of puberty.

Adolescent↗

Incidence of diabetes mellitus in various population groups in Israel (1989 and 1990).

A prospective survey of all newly diagnosed insulin-dependent diabetes mellitus (IDDM) children and adolescents aged 0-17 years in Israel was conducted for the years 1989 and 1990. All diabetic clinics in Israel treating young diabetics were contacted and they returned written reports to us. Each clinic was also visited regularly by a member of the team who reviewed the individual charts to obtain data on population origin as well as medical and demographic data. A total of 187 patients were identified (164 Jews and 23 Arabs), giving a total incidence rate of 5.46/10(5). Analysis of the incidence rates by population groups showed that Arabs and Jews originating in Asia had the lowest incidence (2.77 and 4.58/10(5) respectively), followed by Jews whose fathers were born in Israel (5.61/10(5)). The highest incidence was registered for Jews originating from Europe and North America (9.34/10(5)). The female-to-male preponderance ratio was higher in the Jews originating in Asia (2.1) than in Jews originating in Europe and North America (1.2). Comparing the present data with a survey performed for the years 1975-80 we found a statistically significant increase in incidence in all population groups. Our findings strongly suggest an influence of genetic factors on the incidence of childhood IDDM.

Adolescent↗

GH and GHBP activity and not IGF-1 and its receptor activity express growth velocity reduction during treatment of central precocious puberty by a superactive GNRH analogue.

We studied six patients with central precocious puberty (CPP) (five girls and one boy, aged 9-14.4 years) before and after 5 and 12 months of treatment with GnRH-A (D-TRP-6-LHRH-depo, DECAPEPTYL Ferring, Sweden), and 14 age-matched prepubertal children serving as controls. GnRH suppressed gonadal sex hormone secretion and arrested the gonadarche development. Growth velocity decreased from 9.8 +/- 1.6 (mean +/- SD) to 4.6 +/- 1.0 cm/year after 1 year of treatment. Basal serum IGF-1 levels of the CPP patients were 35.4 +/- 2.8 nmol/l, which was significantly higher than that of the controls (18.8 +/- 1.9, P = 0.00007). After GnRH-A there was a slight but significant increase in serum IGF-1 levels from 35.4 +/- 2.8 (mean +/- SE) to 40.3 +/- 2.1 nmol/l after 5 months (mean difference of 4.9 +/- 1.7, P = 0.02), reversing to 35.6 +/- 2.8 nmol/l after 12 months. The number of high affinity IGF-1 binding sites on erythrocytes (RBC) in the controls was 3.3 +/- 0.3 sites/cell, similar to that found in the patients before treatment. Following therapy, the number of the binding sites decreased from 4.0 +/- 0.8 (mean +/- SE) to 2.5 +/- 0.6 sites/cell after 5 months (mean difference of -1.4 +/- 0.5, P = 0.01), to 2.7 +/- 0.7 sites/cell after 12 months. Basal levels of plasma GH in the CPP patients were 7.1 +/- 1.3 ng/ml, significantly higher than those of the controls (1.2 +/- 0.2, P = 0.00001). Treatment decreased plasma GH in patients from 7.1 +/- 1.3 to 1.3 +/- 0.3 ng/ml after 5 months (mean difference of -5.8 +/- 1.3, P = 0.003) and to 2.7 +/- 1.5 ng/ml after 12 months. The GH binding protein (GHBP) activity in the controls was 76.2 +/- 6.2% relative specific binding, similar to that of the patients before therapy. The mean basal GHBP activity of the patients increased from 75.5 +/- 7.3 to 101 +/- 6.4% (mean difference of 25.5 +/- 9.7, P = 0.01) after 5 months and to 90.1 +/- 5.6% after 12 months of treatment. In conclusion, plasma GH and its receptor activity are a better indicator of the GnRH-A effect on growth than IGF-1 and its receptor activity.

Adolescent↗

Modulation of insulin like growth factor I (IGF-I) binding sites on erythrocytes by IGF-I treatment in patients with Laron syndrome (LS).

The in vivo regulation of IGF-I binding sites was evaluated using erythrocytes (RBC) from 8 patients with Laron syndrome (LS), before and after IGF-I treatment (120-150 micrograms/kg/day s.c.). Basal fasting IGF-I averaged 20.48 +/- 2.06 nmol/l (mean +/- S.E.M.) in the control group as compared to 4.72 +/- 0.84 nmol/l in the 8 LS patients (P = 0.0001). After 1 week of IGF-I treatment serum IGF-I levels increased to 6.53 +/- 1.58 nmol/l (a mean difference of 1.81 +/- 0.95, P = 0.05) and after 1 month of treatment to 14.37 +/- 4.56 nmol/l (a mean difference of 9.37 +/- 4.42, P = 0.03). Concomitantly, we found a significant decrease in the number of high affinity IGF-I binding sites, from 5.74 +/- 0.86 sites/cell (mean +/- S.E.M.) in the non-treated state to 2.29 +/- 0.64 sites/cell and 2.17 +/- 0.53 sites/cell after 1 week and 1 month of treatment, respectively (a mean difference of -3.44 +/- 0.94, P = 0.004 and -3.58 +/- 0.79, P = 0.002, respectively), values similar to those found in the control group. These data demonstrate that replacement treatment of LS patients with IGF-I down regulates its specific receptors. We propose IGF-I binding to RBC as a test to determine the responsiveness of patients considered for long term IGF-I treatment.

Adolescent↗

Familial isolated growth-hormone deficiency with advanced sexual maturation.

Two brothers, aged 15 1/2 and 13 1/2 years, with dwarfism, microcephaly, and advanced sexual and skeletal maturation are described. One patient was mentally retarded. The parents were first cousins. Endocrine studies of these patients documented low growth-hormone levels after clonidine and insulin stimulation and blunted growth-hormone response to growth hormone releasing hormone. Gonadotropin releasing hormone stimulation produced no changes in levels of luteinizing and follicle-stimulating hormones. Basal levels of 17-alpha-hydroxyprogesterone were elevated in the two patients and increased further in response to stimulation with corticotropin. Levels of testosterone, dehydroepiandrosterone sulfate, and androstenedione were variably increased in both patients and showed a proportional increase on stimulation with human chorionic gonadotropin. To our knowledge, this is the first report of a familial association between growth-hormone deficiency and advanced bone and sexual maturation. A pituitary and an independent adrenal defect could account for the observations in these patients, but in view of the familial recurrence, a common underlying defect is possible.

Adolescent↗

Insulin enhances the growth of cartilage in organ and tissue cultures of mouse neonatal mandibular condyle.

Condylar cartilages were cultured in the form of organ cultures on top of collagen sponges in medium containing 2% fetal calf serum and were treated with 3.5-350 nM insulin for 6 days. Doses of 175 nM of insulin caused a marked increase (+96%) in DNA synthesis and in proteoglycan production (+74%), features that manifested themselves structurally by a 60% increase in overall size of the cultured explants. Using a tissue culture system comprised of cartilage progenitor cells, insulin was found to enhance the differentiation of the progenitor cells so that by 6 days in culture an appreciable nodule of differentiated chondrocytes developed. The latter was surrounded by perichondrial cells whereas the extracellular matrix within the newly formed, insulin-induced, nodule reacted positively for cartilage-specific antigens (type II collagen and bone sialoprotein). It is suggested that insulin induces a direct stimulatory effect on progenitor cell proliferation, cartilage differentiation, and extracellular matrix deposition.

Animals↗