Nonsuppressible Insulin-Like Activity (NSILA).II. Regulation of Serum Concentrations by Growth Hormone and Insulin*

Heinrich, U.; Schalch, Don S.; Koch, Janet G.; Johnson, Carolyn J.

doi:10.1210/jcem-46-4-672

Cited by 32 publications

(6 citation statements)

References 28 publications

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“…As reported earlier, total IGF is elevated in acromegalic and decreased in hypopituitary pa¬ tients (Schlumpf et al 1976;Zapf et al 1977;Heinrich et al 1978). However, the increase of total IGF in acromegalics is exclusively due to an increase in immunoreactive IGF I.…”

Section: Resultssupporting

confidence: 71%

Serum levels of insulin-like growth factor (IGF) and its carrier protein in various metabolic disorders

Zapf¹,

Morell²,

Walter³

et al. 1980

Acta Endocrinologica

131

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Abstract. The levels of insulin-like growth factors (IGF), two somatomedin-like polypeptides of human serum and of their carrier protein were determined in sera of patients with various metabolic disorders. IGF was measured by 4 different methods (fat pad and fat cell assay and competitive protein binding assay measuring total IGF, and a radioimmunoassay for IGF I) after extraction by acidic gel filtration on Sephadex G-50. This procedure is necessary to separate IGF from the carrier protein, which interferes with all of these assays. 1) In normal serum, immunoreactive IGF I accounts for one third of total IGF determined by the fat pad assay, but only for one fifth to one sixth of immunoreactive IGF I + II. 2) In acromegalics total IGF was increased 1.5- (protein binding and fat cell assay) to 2-fold (fat pad assay), but the increase was solely due to immunoreactive IGF I, which was ∼ 5-times above normal. The IGF binding activity was not elevated. Total IGF and IGF binding were decreased in hypopituitarism, Laron-type dwarfism and in liver cirrhosis. Immunoreactive IGF I was more drastically reduced in these diseases than total IGF. Apparently, only IGF I is under growth hormone control. The liver seems to be involved in the production of IGF. 3) No elevation of total IGF was found in patients with extrapancreatic tumour hypoglycaemia, but IGF binding was reduced. Immunoreactive IGF I was decreased in 5 of 10 patients. These results suggest that tumour hypoglycaemia in our patients is unlikely to be caused by increased IGF levels. 4) In patients with hyperprolactinaemia neither total IGF nor immunoreactive IGF I were elevated, and IGF binding was unchanged. 5) In newly detected insulin-deficient juvenile diabetics total IGF and immunoreactive IGF I levels were within the normal range, although the variation was greater than in normal subjects. However, IGF binding was markedly decreased.

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Section: Resultssupporting

confidence: 71%

Serum levels of insulin-like growth factor (IGF) and its carrier protein in various metabolic disorders

Zapf¹,

Morell²,

Walter³

et al. 1980

Acta Endocrinologica

131

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“…A high concentration of growth hormone during the first 2 months of life was found by these authors, closely followed by somatome din activity. This corresponds to our results in this study, and correlates well with an accelerated growth rate dur ing this period, observed by us [7| as well as other authors [13], Furthermore, low concentrations of carrier protein during this lime indicate a high level of free, available somatomedin activity, as the biological activity of somatomedins appears to be regulated at least partly by circulating levels of their carrier proteins [14]. Fur thermore, an increased sensitivity of cartilage to somatomedins in young animals points to the great importance of these growth promotors during this period of life ] 15].…”

Section: Discussionsupporting

confidence: 93%

Inhibitory Activity of Cartilage Growth in Serum of Young Rats

Kvinnsland¹,

Kvinnsl²

1984

Cells Tissues Organs

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Humoral factors play an important role in growth regulation. The growth regulatory activity in serum is a complex system with both growth-promoting and growth-inhibiting factors. In this study, using in vitro cartilage from rat nasal septum as target organ, evidence is presented that inhibiting activity does exist in normal rat serum. This activity seems to play a role in modulating cartilage growth rate in young, normal animals. Furthermore, a significant interaction between age in cartilage and age in serum as regards influence on cartilage growth was found.

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“…The liver BPs therefore seem to have a preferential affinity for the more GH-dependent IGFs of the type SM C/IGF I. In this they differ from the BPs extracted from human serum, which have a greater affinity for IGF II (5) and which give a poor discrimination between normal and acromegalic sera (6,7), since the rise in IGF levels is attributable mostly to increases in IGF I (8).…”

mentioning

confidence: 92%

Evidence for Production by the Liver of Two Igf Binding Proteins With Similar Molecular Weights but Different Affinities for Igf I and Igf Ii. Their Relations With Serum and Cerebrospinal Fluid Igf Binding Proteins.

Binoux

Hardouin

Lassarre

et al. 1982

The Journal of Clinical Endocrinology & Metabolism

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Studies of the competitive binding of IGF I and IGF II and 125I-labelled IGF I and IGF II to the specific binding proteins (BPs) produced by the liver in culture suggest that two BPs exist, one with a selective affinity for IGF I and the other with a selective affinity for IGF II. The ratio of the former BP to the latter appeared to be higher in the culture medium of young rat livers and of fetal human livers than that in the culture medium of adult human livers. The two BPs form complexes with their IGFs with the same apparent molecular weight of approximately 40K. With gel filtration of adult human serum both types of BP eluted with the greater than 100K and the 40-70K molecular weight material. The BP with the selective affinity for IGF II predominated in the 40-70K material as well as in the cerebrospinal fluid of adult human subjects.

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Nonsuppressible Insulin-Like Activity (NSILA).II. Regulation of Serum Concentrations by Growth Hormone and Insulin*

Cited by 32 publications

References 28 publications

Serum levels of insulin-like growth factor (IGF) and its carrier protein in various metabolic disorders

Serum levels of insulin-like growth factor (IGF) and its carrier protein in various metabolic disorders

Inhibitory Activity of Cartilage Growth in Serum of Young Rats

Evidence for Production by the Liver of Two Igf Binding Proteins With Similar Molecular Weights but Different Affinities for Igf I and Igf Ii. Their Relations With Serum and Cerebrospinal Fluid Igf Binding Proteins.

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