ISSN:1663-2818    

DOI:10.1159/000180543

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:1663-2818    

DOI:10.1159/000180544

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:1663-2818    

DOI:10.1159/000180545

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

The isolation and characterization of growth hormone-releasing factor (GRF) has initiated a new and exciting era in our understanding of the neuroendocrine regulation of pituitary growth hormone (GH) secretion. This report briefly describes the isolation and characterization of GRF, factors which modulate the GH response to GRF and the effects of chronic administration and deprivation of GRF on somatic growth. The intent of this report is to serve as a general introduction on biochemical and physiological aspects of GRF. The following reports from this symposium will then cover many of these topics in much greater detail.

ISSN:1663-2818    

DOI:10.1159/000180546

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

GHRH was isolated from two GHRH-secreting pancreatic tumors which resulted in clinical acromegaly. Over 98% of acromegalic patients have a pituitary adenoma; however, acromegaly may occasionally result from ectopic or eutopic GHRH secretion. Administration of GHRH to normal adults stimulates growth hormone (GH) secretion; it may also stimulate GH release in some adults with GH deficiency in childhood and in a majority of GH-deficient children. Continuous infusion of GHRH to normal men stimulates GH secretion which augments naturally occurring GH pulses. GHRH is effective when administered subcutaneously and intranasally, but requires 30- and 300-fold higher doses, respectively. Intermittent subcutaneous GHRH therapy promotes acceleration of linear growth in GH-deficient children and appears promising as a treatment for these children.

ISSN:1663-2818    

DOI:10.1159/000180547

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

A dose-effect relationship between human growth hormone (GH) releasing factor (hGRF) and GH response was demonstrated for doses ranging from 5 µg per subject (minimal active dose) to 40–80 µg per subject (minimal dose for maximal effect). Bioactivity of GH released under hGRF was proven in the Nb2 lymphoma cell multiplication assay. Unwanted effects were observed for doses equal to or larger than 150 µg. Pharmacokinetic parameters were calculated from the immunoreactive GRF plasma concentrations obtained after intravenous injections of various doses. The half-lives were 6.8 ± 0.4 min and 43.2 ± 3 min for distribution and elimination phases, respectively. Subcutaneous administration of hGRF was shown to be effective for promoting GH release, with doses higher than those required by intravenous administration. Intermittent intravenous injection of hGRF, at 3-hour intervals, resulted in a decrease in the magnitude of GH response in normal su

ISSN:1663-2818    

DOI:10.1159/000180548

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

In untreated acromegalic patients, mean serum level of insulin-like growth factor (IGF) is two times higher than in controls, and all patients have IGF values above the mean + 2 SD of the controls, while some of these patients have normal GH values. After treatment, clinical status correlates better with IGF than with GH. Thus, measurements of serum IGF can be helpful in the diagnosis of acromegaly and in assessment of the efficiency of therapy.

ISSN:1663-2818    

DOI:10.1159/000180549

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Plasma growth hormone releasing factor (GHRH) was measured by RIA in the plasma of 41 children with constitutionally short stature. Basal plasma GHRH was 51 ± 10 pg/ml. L-Dopa induced a 2-fold increase in circulating GHRH 30–45 min before the elevation of GH. A positive correlation (p < 0.005) was found between the peak of GH and GHRH during the dopaminergic stimulus. On the opposite, the secretion of GH induced by amino acids or clonidine is not preceded by an elevation of plasma GHRH. When a release of GH appeared after the insertion of the venous catheter alone, probably due to the stress, it was preceded by a rise of plasma GHRH. In four sleeping adolescents during the night no relationship was found between the peaks of plasma GHRH and the peaks of GH secretion. These results suggest that the various stimulations of GH secretion used for investigations of a short stature do not act in the same way at the hypothalamo-pituitary lev

ISSN:1663-2818    

DOI:10.1159/000180550

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Insulin-like growth factors (IGFs, somatomedins) are structural homologues of insulin with insulin-like biological activity. They are mainly synthesized and secreted by the liver, but may also be produced by extrahepatic tissues. In their native from in blood they are bound to specific carrier protein(s). This determines essentially their biological actions. The complexed factors stimulate growth indices in vitro and in vivo, but, in contrast to the free factors, do not exert acute effects on insulin target tissues.

ISSN:1663-2818    

DOI:10.1159/000180551

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

The primary structure of the somatomedins (SM) IGF-I and IGF-II has been known for some years. Both from isolation of the SMs from plasma and from the study of cDNAs it has become evident that there are more SMs, needing further study. In plasma the SMs are present in larger molecules of two size-classes: 150 kD and 40 kD, behaving as specific SM-binding proteins. The possibility that such protein classes are heterogeneous and also contain precursor molecules undergoing proteolytic processing is considered. The somatomedin genes are discontinuous and span large regions of the human genome.

ISSN:1663-2818    

DOI:10.1159/000180552

出版商:S. Karger AG    

年代:1986

数据来源: Karger