[Insulin-like growth factor 1 (somatomedin C) and its binding proteins 1 and 3 in children with special consideration of diabetes].
Insulin-like growth factor 1 (IGF-1, somatomedin C) belongs to a family of polypeptide hormones, which are structurally close relatives of insulin. Circulating IGF-1 is synthesised in the liver. Serum level of somatomedin is regulated by: growth hormone (GH), insulin and nutrition. It is also produced locally by most tissues, where it acts in auto- and paracrine manner. IGF-1 takes part in regulating growth after binding to IGF receptor during embryonic development and after birth. In adults somatomedin plays a role in the process of regeneration, mainly in the case of connective tissue. It is also a weak mitogen for most cultured cells and it can act like insulin. Somatomedin circulates in plasma in complex with a family of binding proteins. 85-95% of total IGF-1 is found in the complex consisting of IGF-1, binding protein 3 and ALS. This complex is a store of IGF and limits the access of somatomedin to specific receptors. After binding with IGFBP-1, IGFBP-2 and IGFBP-6, IGF-1 passes through epithelium and reaches the target cells. The serum concentration of this protein appears to be inversely related to insulin level. IGFBP-1 can modulate IGF growth-promoting effect. IGF and its binding proteins are important in the diagnosis and treatment of some pituitary diseases, catabolic states such as malnutrition, burns, AIDS, polytrauma and tumors with hypoglikemia. Insulin-like growth factors may be involved in the etiopathogenesis of diabetes and in diabetes complications. Abnormalities in functioning of GH-IGF-1 axis are regarded as a cause of the growth retardation in children with poor metabolic control of type 1 diabetes, insulin-resistance, dawn phenomenon and fat disorders. rhIGF has been used in the treatment of some diseases bringing positive results.
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