Effects of increased doses of 1,25 dihydroxyvitamin D3 on matrix and DNA synthesis in condylar cartilage of suckling mice.

The in vivo effects of high doses of 1,25(OH)2D3 were studied in condylar cartilage of suckling mice. Seven-day-old animals were treated with 20 ng of the hormone for 7 consecutive days. Biochemical assays on collagen content and synthesis were complemented by structural studies using light and electron microscopy.

Dexamethasone impairs growth and collagen synthesis in condylar cartilage in vitro.

The in vitro effects of dexamethasone on condylar cartilage from normal newborn mice were tested by measuring protein and DNA content, collagen synthesis, prolyl hydroxylase activity, collagen chains and by immunofluorescence the localization of type I and II collagen and fibronectin. The biochemical assays were complemented by structural studies of hormone-treated and control cultured specimens. It became apparent that both the protein and DNA content of the tissue decreased immediately following the addition of dexamethasone of the incubation system.

Effect of short-term physical stress on DNA and collagen synthesis in the femur of young and old mice.

Aging of long bone in the hindleg of the mouse is accompanied by a progressive cavitation of the cortical bone along with clear atrophic structural changes characteristic of senile osteopenia. Quantitative analysis indicates that there is a nonsignificant change in the DNA content, but an increase in the protein percentage of the total bone wet weight. Bones of old animals incorporate significantly less (3H)-thymidine and markedly less (3H)-proline.

Analysis of collagen types synthesized by rabbit ear cartilage chondrocytes in vivo and in vitro.

This study compares the collagen types present in rabbit ear cartilage with those synthesized by dissociated chondrocytes in cell culture. The cartilage was first extracted with 4M-guanidinium chloride to remove proteoglycans. This step also extracted type I collagen.

Isolation and characterization of a precursor form of M collagen from embryonic chicken cartilage.

A disulfide-cross-linked collagen has been extracted with neutral salt solutions from organ cultures of embryonic chick sternal cartilage. This collagen, which we term pM collagen, is presumed to be the native extracellular precursor molecule to disulfide-cross-linked collagen fragments recently described. Cleavage of pM collagen under native conditions with pepsin gives rise to the collagen fragments M1 and M2, which had also been isolated from pepsin extracts of chick hyaline cartilage [K.

Isolation and characterization of new collagens from chick cartilage.

Three unique collagen chains were isolated from chick sternal cartilage following pepsin solubilization of total cartilage collagens and removal of the predominant type II collagen by fractional salt precipitation. Native molecules containing 1 alpha, 2 alpha and 3 alpha chains precipitated between 0.7 M and 1.