| Popis: |
Insulin-Like Growth Factors-I and -II are potent mitogenic peptides that are synthesized by many cell types in mammals (Sara and Hall, 1990, Styne, 1998). These hormones appear to be important in growth regulation of the organism, including during perinatal life (Cohick, et al., 1993,Philipps, et al., 1988). This presumption is strengthened by recent observations of mice bearing nonfunctional genes for IGF-I, -II (Baker, et al., 1993,Lau, et al., 1994), since these have significant growth restriction as well as a high perinatal mortality rate. Attention has also recently focused upon the presence of IGF’s in milk of many species in biologically relevant concentrations. Studies from our laboratories (Philipps, et al., 1991) as well as others (Donovan, et al., 1990) have shown that IGF-I and -II are present in the milk of at least several species. IGF’s are present in most biological fluids in close association with binding proteins and it has been suggested that these binding proteins play a significant role in modulation of IGF-receptor interaction and as a potential reservoir for IGF in the circulation. The serum concentration of IGFBP, particularly BP2 in the suckling, may be responsive to levels of nutritional sufficiency. |
