Change in response with age of human articular cartilage to plasma somatomedin activity

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Abstract
Normal male articular cartilage (34 specimens, age range 1–30 years) has been examined in vitro for response to somatomedin (SM) activity. Basal3H-thymidine and35S-sulfate incorporation both decreased with increasing age of the cartilage donor. However, enhancement of isotope incorporation which was attained on addition of 10% normal plasma (containing IU SM/ml) was greatest in cartilage from adolescents in the age range 12–17 years. The mean enhancement of3H-thymidine incorporation (expressed as % basal) was as follows: age 1–10 years=184 ± 28 (SE),N=9; 12–17 years=436 ± 101 (11); 18–30 years=231 ± 49 (8); and for35S-sulfate incorporation was 1–10 years=389 ± 100 (8); 12–17 years=824 ± 273 (11); and 18–30 years=572 ± 56 (8). The increased response of cartilage in the 12–17 year group suggests that a greater sensitivity to the somatomedins may contribute to the increased skeletal growth during adolescence.