Antibodies to a precursor of human collagen

Tissue calcification and inflammation in osteoarthritis

Clinical evidence of inflammation and the presence of calcium phosphate crystals in the joint fluid are both characteristics frequently seen in osteoarthritic patients. However, the relevance of the crystal deposition to the pathogenesis of osteoarthritis remains unclear. In this study of 28 patients with advanced osteoarthritis the frequency and type of crystal deposition has been investigated and the relationship between tissue inflammation and crystal deposition has been explored. Tissue calcification, though present in all patients, is but one of several intra-articular inflammatory agents. Its relevance to inflammation in osteoarthritis is discussed.

Biochemical characteristics and biological significance of the genetically-distinct collagens

In recent years it has become evident that genetic polymorphism is dramatically expressed in the structural protein, collagen. Current information on the biochemical properties, biosynthesis, and tissue distribution of Type I, II, and III collagens is summarized with special reference to possible unique functional roles fulfilled by each of these collagens.

Radioimmunoassay for the aminoterminal peptide of procollagen p alpha 1(I)-chain

Peptides derived from the aminoterminal portion of the palpha1(I)-chain of calf and sheep procollagen were labeled with iodine-125. Despite changes in electrophoretic homogeneity after labeling, reaction of the labeled peptide with antisera to unlabeled peptide was retained. Antisera to procollagen or the isolated procollagen peptide showed high titers for the native peptide, a much weaker binding with the reduced and alkylated peptide and little or no reaction with collagen. Antisera to collagen showed strong binding with collagen and a weaker but distinct reaction with the procollagen peptide. Evidence was obtained that a minor contaminant of procollagen peptide was present in the acid-extracted collagen and that there were no shared antigenic determinants. Bovine serum and amniotic fluid contained 1-10 mug/ml reactive antigen. These results indicate that the labeled peptides can be used as a specific, sensitive and accurate assay for the amino-terminal portion of procollagen in biological samples.

Procollagen peptidase: its mode of action on the native substrate

Procollagen peptidase was recovered from the medium of human and mouse fibroblast cultures by precipitation with ammonium sulfate. The test substrate for the in vitro enzymatic reaction was radioactively-labeled, disulfide-linked procollagen prepared from the medium of human fibroblast cultures. The enzymatic digests were analyzed by electrophoresis in polyacrylamide gets containing sodium dodecyl sulfate and urea. The human and mouse enzymes reacted with the substrate to generate the same intermediates and final products. Procollagen peptidase acts as an endopeptidase which cleaves each of the three procollagen chains in turn. The final products of the reaction are collagen and a three-chain, disulfide-linked fragment derived from the nonhelical aminoterminal residues of procollagen.

Radioimmunoassay for human procollagen

Rabbit antiserums were produced against the procollagen molecule secreted into the medium of cultured human skin fibroblasts. The isolated antigenic, amino terminal portion of the procollagen molecule was purified, labeled with iodine-125, and used in a radioimmunoassay which detected nanogram quantities of the same antigen. With the assay, immunologically identical molecules were detected in the culture mediumn of different strains of human fibroblasts and in normal human serums. Serumns from human cord blood contained a 12-fold higher concentration of the antigen than serums from adults, while serums other vertebrates gave reactions to incomplete cross-reactivity or non-reactivity.