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Biomedical subjects

Z Laron

Publications and source records attributed to Z Laron.

At least 253 records · Page 14Linked to original sources
PubMed1981

Occurrence of four types of growth hormone-related dwarfism in Israeli communities.

Data are presented on 121 dwarfed patients belonging to 98 Israeli families with 4 types of dwarfism related to deficiency or in activity of human growth hormone (hGH): isolated growth hormone deficiency (IGHD), partial hGH deficiency (pIGHD), multiple pituitary hormone deficiencies (MPHD) and Laron-type dwarfism (LTD). These series are believed to comprise most of the dwarfs of these types in Israel; however, their distribution among the various ethnic communities varies greatly: LTD (15 families) is confined to a few communities of Oriental Jews; only 3 of 30 families with IGHD, but 7 of 10 families with pIGHD, are Ashkenazi, whereas the clinic distribution of 42 families with MPHD corresponds roughly to that of the general population. These data seem to reflect the role of genetic factors in the etiology of the various types of dwarfism: the stronger the genetic component, the greater is its deviation from random occurrence among the various communities.

Dwarfism, Pituitary↗
PubMed1981

Long-term effect of D-Trp6-luteinizing hormone-releasing hormone on testicular size and luteinizing hormone, follicle-stimulating hormone, and testosterone levels in hypothalamic hypogonadotropic males.

Six men, ages 18 to 34 years, with hypothalamic hypogonadotropism were treated with D-Trp6-luteinizing hormone-releasing hormone (10 micrograms intramuscularly on alternate days) for a period of 6 months. They underwent an intravenous luteinizing hormone-releasing hormone (LH-RH) test (50 micrograms/sq m) before and after 1, 3, and 6 months of treatment. During the first 3 months of therapy, the mean (+/- standard deviation) testicular volume increased from 3.5 +/- 1.0 ml to 6.0 +/- 2.0 ml, but decreased to 5.0 +/- 1.0 ml after 6 months. A significant increase in the plasma LH response to LH-RH over pretreatment levels was noted after 1 month (10.2 +/- 4.2 mIU/ml versus 1.6 +/- 1.0 mIU/ml, P less than 0.001) and 3 months (3.0 +/- 1.6 mIU/ml, P less than 0.01) with a subsequent decline to pretreatment levels after 6 months of treatment. The follicle-stimulating hormone response to LH-RH was not significant. It is concluded that D-Trp6-LH-RH induced an initial stimulation in these patients but, probably because of the excessively high dose used, a paradoxical inhibitory response was obtained after 3 months of therapy.

Adolescent↗
PubMed1981

Rise in plasma growth hormone in response to exogenous LRH in Klinefelter's syndrome.

In a group of sixteen patients with Klinefelter's syndrome (KS) aged from 2 years 8 months to 31 years, a study was made of the plasma growth hormone (hGH) response to LRH (50 micrograms/m2 i.v.; n=16), TRH (200 micrograms i.v.; n=14) and insulin-induced hypoglycaemia (0.1 u R.I,/kg i.v.; n=6). There was a rise in hGH following LRH from a level below 5 ng/ml during fasting to a level above 8 ng/ml (P less than 0.001) in nine (56.3%) of the sixteen patients tested; a similar response was found in only one of a control group of fifteen boys matched for age. TRH stimulation led to a rise in hGH in one of the fourteen KS patients tested, with none in the control group. Insulin-induced hypoglycaemia elicited a normal response of hGH in the six KS patients tested, from 1.8 +/- 0.7 to 16.5 +/- 3.7 ng/ml, (M +/- SD, P less than 0.001). Basal prolactin (PRL) levels were normal in the KS patients (9.4 +/- 4.1 ng/ml, M +/- SD) but the response to TRH stimulation was significantly higher (63.3 +/- 40 ng/ml; P less than 0.01) than that of the control group (30 +/- 15 ng/ml). Plasma gonadotrophin levels and the response to LRH stimulation were increased in all of the KS patients except those below the age of 13. Plasma TSH levels and the response to TRH stimulation as well as the levels of serum thyroxine were found to be normal in all the KS patients tested. The abnormal rise of hGH following LRH stimulation and of PRL following TRH stimulation suggests a disturbance in the neuroendocrine regulation mechanisms of these hormones in KS.

Adolescent↗
PubMed1981

Addison's disease associated with precocious sexual development in a boy.

An eleven-year-old boy was diagnosed to have Addison's disease with an ACTH level of over 4500 pg/ml after a short episode of fever and dehydration. From the age of 6 years his skin and buccal mucosa had been hyperpigmented but there were no other subjective complaints. The clinical examination also revealed signs of advanced puberty for his age (3rd--4th stage according to Tanner's criteria), with advanced bone age (13 years). The elevated levels of plasma testosterone and gonadotropins and their response to LH-RH stimulation were appropriate for his clinical stage of puberty and supported the diagnosis of true precocious puberty. It is proposed that the concomitant appearance of Addison's disease and precocious puberty is due to a "drift" phenomenon of LH-RH and/or gonadotropins following the prolonged elevation of ACTH secretion.

Addison Disease↗
PubMed1981

Abnormal growth hormone response to LRH and TRH in adolescent schizophrenic boys.

The authors studied the effect of LRH and TRH on HGH in 10 adolescent schizophrenic boys and 9 age-matched normal boys. Before antipsychotic treatment, LRH and TRH induced a marked rise in hGH in 8 of 10 patients and 4 of 6 patients, respectively. No effect on HGH was observed in the normal controls. After 3 months of treatment with chlorpromazine, thioridazine, or haloperidol, LRH failed to induce a rise in HGH in 5 of the 6 patients tested, but TRH induced a significant rise in HGH in 3 of 4 patients tested. The authors postulate that these results indicate a dysfunction in the mechanism regulating HGH secretion in schizophrenia.

Adolescent↗
PubMed1981

The effect of insulin-like growth factor (IGF) and of human serum on steps in proteoglycan synthesis.

Embryonic chick pelvic cartilages were incubated in the presence of insulin like growth factor (IGF) (1 - 100 microunits/ml), as well as normal human serum (5%), with radiolabelled precursors of proteoglycan (PG) synthesis: L-[3-3H]serine, D-[6-3H]glucosamine and [35S]Na2SO4. IGF alone (1 - 15 microunits/ml), stimulated in a dose-dependent manner D-[6-3H]glucosamine incorporation into tissue-bound and soluble isolated glycosaminoglycan (GAG) chains. L-[3-3H]serine incorporation into PG molecules was not stimulated by IGF (1 - 100 microunits/ml), despite the increase in the uptake of this precursor into intact cartilage. [35S]Na2SO4 incorporation was unaffected by IGF. Serum promoted the uptake of all three precursors into tissue-bound glycosaminoglycans. It was postulated that IGF could stimulate proteoglycan synthesis not only by elongating existing chondroitin sulphate chains but also by increased synthesis of other sugar chains e.g. keratan sulphate and oligosaccharides.

Animals↗
PubMed1980

Puberty in Laron type dwarfism.

The onset and progress of puberty was followed in 18 patients (7 males and 11 females) with Laron-type dwarfism (LTD). The boys had delayed puberty, testicular enlargement occurring between 12--14 years being the first sign. The first conscious ejaculation occurred between 17--21 years and full maturity was reached after the age of 22. In girls menarche occurred between 13--14 years and full maturity was reached between 16-19 years. Two patients--one male and one female--have children.

Adolescent↗
PubMed1980

Hormonal and local agents as extracellular regulators of cartilage growth measured by the rate of proteoglycan synthesis. A hypothesis.

Following the rate of proteoglycan synthesis as the metabolic parameter of the growth of cartilage cells, indicates that hormonal and local agents are two distinct types of extracellular regulators responsible for altering the basic metabolic rates of cells. Such changes in growth rate occur regularly at physiological developmental stages (e.g., during embryonic life and at advancing age), and at pathological events (e.g., wounds and repair).

Animals↗
PubMed1980

Follow-up of boys with unilateral compensatory testicular hypertrophy.

Of a total of 148 boys with unilateral compensatory testiculary hypertrophy (CTH) diagnosed at our clinic, 30 were followed for many years throughout puberty. These boys underwent the pubertal stages fo pubic hair development in a normal manner, including penile growth. The basal plasma levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) of the boys with CTH showed a wider range than those of normal boys. Even in prepuberty the mean basal plasma FSH levels were significantly higher than those of normal boys, as was the peak FSH response to intravenous LH-releasing hormone. In puberty stage 4 the mean plasma LH levels were also higher than normal. Plasma testosterone levels were within the normal range in pubertal stages 1 to 4, but in stage 5 the mean basal level and response to stimulation with human chorionic gonadotropin were significantly lower than normal. Among seven spermatograms performed, five showed oligospermia and two showed azoospermia. It is concluded that compensatory hypertrophy of one testis does not seem able to prevent testicular insufficiency in adulthood.

Adolescent↗
PubMed1980

Evaluation of the renin-aldosterone system during hypo- and hyperglycemia in children and adolescents.

The effect of hypo- and hyperglycemia on the renin-aldosterone system was studied in 10 endocrinologically normal children. Insulin-induced hypoglycemia caused an elevation of plasma renin activity (PRA) up to 371 +/- 23% (mean +/- SEM) over the basal level (p less than 0.001) and of the plasma aldosterone level up to 243 +/- 7% (mean +/- SEM) over the basal values (p less than 0.001). Hyperglycemia caused an elevation of PRA up to 135 +/- 40% (mean +/- SEM) over the basal values (p less than 0.05) and a reduction in the plasma aldosterone level to 53 +/- 12% (mean +/- SEM, p less than 0.01). It is suggested that the widely used diagnostic procedures, the insulin tolerance and oral glucose tolerance tests, be also applied for the investigation of the renin-aldosterone system.

Adolescent↗