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J Zapf

Publications and source records attributed to J Zapf.

220 records · Page 13Linked to original sources
PubMedDate not supplied

Growth restoration of insulin-deficient diabetic rats by recombinant human insulin-like growth factor I.

Insulin-like growth factor I (IGF-I) and insulin stem from a common precursor, are structural homologues, act through similar receptors and elicit insulin-like and growth-promoting effects in vitro and in vivo. Serum IGF-I levels are controlled by growth hormone, insulin and nutrition. Insulin-deficient growth-arrested diabetic animals have reduced serum IGF-I levels which are restored towards normal by insulin but not by growth-hormone treatment. Here we show that normal growth of diabetic rate is restored by infusion of recombinant human (rh)IGF-I without normalization of the blood sugar level and that insulin acts via an increase of IGF-I synthesis on growth of diabetic rats. We describe a new mechanism of endocrine control of growth in which IGF-I is the major stimulator at the cellular level. Growth hormone and insulin act mainly by modulating the hepatic synthesis of IGF-I.

Animals↗
PubMedDate not supplied

Comparison of pancreatic human and biosynthetic human insulin with respect to their action on adipocytes and chick embryo fibroblasts.

Biosynthetic human insulin (BHI) was compared to pancreatic human insulin and sperm whale insulin in terms of ability to stimulate incorporation of glucose into isolated rat adipocytes and thymidine into DNA in chick embryo fibroblasts. The human insulins were identical in their effects in both assays. Sperm whale insulin was more potent than the human insulins in stimulating glucose incorporation into rat adipocytes. All three insulins showed identical stimulation of DNA synthesis in the fibroblast assay. That action, however, is mediated via the receptor for insulin-like growth factor (IGF-I). Therefore, both human insulins were evaluated in terms of binding to the IGF-1 receptor in chick embryo fibroblasts. The two human insulins behaved identically (and agreed with previous findings for sperm whale insulin). All insulins, however, were approximately 200-fold less potent than IGF-I itself in this binding assay.

Adipose Tissue↗
PubMedDate not supplied

[Growth factors with identical insulino-situations : IGF I and II, NSILA and somatomedins (author's transl)].

NSILA consists of two polypeptides of known structure. IGF I and II are close relatives of insulin. 50% of all amino acid residues in the A-and B-region of IGF I and II are situated in identical positions as in the A-and B-chain of insulin. A C-region of 12 and 8 residues respectively connects the A-and B-region in IG FI and II. A D-region of 8 and 6 residues extends the A-region of IGF I and II. 17 of all invariable 19 amino acid residues in the insulin molecules of all known species are also present in IGF. IGF is attached to a carrier protein in serum. The latter inhibits its action on adipose tissue and muscle. Therefore, IGF cannot be measured in serum but, rather, must be dissociated from the binding protein before quantitation. Most tissues appear to have IGF binding sites for which insulin does not compete with the exception of fibroblasts. IGF probably acts via interaction with the IGF receptor, with the exception of adipose tissue where the IGF effect is mediated by the insulin receptor. The concentration of IGF I in serum is under growth hormone control. It is elevated in acromegalics and decreased in pituitary dwarfs and Laron dwarfs. IGF I and II are potent stimulators of cell growth in culture. Their growth stimulating effect in vivo has not yet been unequivocally proven.

Acromegaly↗