Collagen glucosyl- and galactosyltransferases of cultured human fetal lung fibroblasts

Increased prolylhydroxylase activity in chondrocytes but not synovial cells from adjuvant arthritic rat knees

Prolylhydroxylase and galactosylhydroxylsyl glucosyl (GGH) transferase were assayed in cells cultured from cartilage and synovium (adipose type) removed from normal and adjuvant arthritic rat knees. There was a significant increase in prolylhydroxylase in chondrocytes from arthritic knees compared to the normals but no change in GGH transferase activity was found. In the cells derived from the synovium no variation in either enzyme was observed. No significant changes in DNA or protein content was found in either type of cells from the arthritic joints. Comparison of the prolylhydroxylase activity in the supernatant and pellet fractions prepared from chondrocytes from normal and arthritic joints, demonstrated that the majority of the activity was recovered in the supernatant fraction rather than the pellet in arthritic chondrocytes. The data presented indicate that the degree of hydroxylation of cartilage collagen alters in arthritis.

Changes in the higher order organization of DNA during aging of human fibroblast-like cells

Nucleosome spacing (DNA repeat length) was determined in human diploid fibroblast-like cells (HDF) of different in vitro ages following the electrophoretic separation of micrococcal nuclease digestion products. The results indicate that a heterogeneity of DNA repeat lengths is present in HDF of all in vitro ages. In older cells the organization of part of the DNA is conserved, but a greater proportion of shorter repeats is evident. The shorter repeat lengths are not due to nucleosome sliding, but result from the presence of shorter linker regions which are reduced by as much as 25% in part of the chromatin of high PDL cells.