Alfred Angrist

Effect of puromycin and salicylate on biosynthesis of mucopolysaccharides and glycoproteins in bovine heart valve

Abstract Two isotopes ( 3 H-glucosamine and 14 C-threonine) were used simultaneously to study the effects of puromycin and salicylate on the in vitro biosynthesis of hexosamine-containing substances in bovine heart valves. Papain digests of fragmented valve tissue incubated with precursors 14 C-threonine and 3 H-glucosamine were divided into mucopolysaccharide and glycopeptide fractions by gel filtration, and the radioactivities of 3 H and 14 C in the two fractions were determined in order to compare the individual biosynthetic activities of the carbohydrate and peptide moieties in them. Puromycin (9 × 10 −4 M ) inhibited completely the uptake of 14 C-threonine and also the uptake of 3 H-glucosamine considerably; the inhibition in the glycopeptide fraction was more marked than in the mucopolysaccharide fraction; moreover, labeling of glucosamine was less than it was for galactosamine in the mucopolysaccharide fraction. The implication is that the synthesis of the polysaccharide chain depends upon the basic or prior formation of the protein backbone. In the presence of salicylate (1.5 × 10 −2 M ), the incorporation of both labeled substrates was less for the mucopolysaccharide than for the glycopeptide fraction; also labeling of galactosamine was largely inhibited in both fractions. Salicylate seems to act at several possible sites in the synthesis of the carbohydrate-protein complex in addition to its effect on the amino sugar formation; therefore, the biosynthesis of mucopolysaccharide, especially galactosamine-containing substances, is inhibited more by salicylate, possibly because of this multiplicity of potential sites of action in its more complicated biosynthesis.

Collagen and platelet interaction in experimental vegetative cardiac valvular lesions

Abstract Miniature (nonbacterial) platelet thrombi of the cardiac valve were produced by either a single injection of SHU (Chinese Red) or by a direct needle puncture in the rat. The early sequential changes in the formation of miniature platelet thrombi on the valve, as described, indicate an in vivo interaction of collagen to platelet, with resultant platelet clumping.

Some preliminary observations on the mucopolysaccharide and glycoprotein formation in bovine heart valves

Abstract Bovine aortic and pulmonary valves were incubated with labeled glucosamine. Both mucopolysaccharide and glycopeptide fraction in these tissue incorporated radioactive material. The biosynthetic activities of both substances were higher in the aortic than in the pulmonary valve. In both valves, the carbohydrate moieties in glycoproteins may be more rapidly synthesized than mucopolysaccharides.

The in vitro biosynthesis of collagen in bovine heart valves

Abstract Bovine heart valves of different ages were incubated with l -proline-3H for the study of collagen biosynthesis. The synthesis of collagen in the heart valves, especially in the young, is quite active. The specific activity of hydroxyproline in collagen in all heart valves decreased with increasing age. The biosynthetic activity in the mitral valve was higher than in that of the other cardiac valves. The specific activity of hydroxyproline in the fibroblast-rich portion of the old bovine heart valve was comparatively higher than in the chondroblast-rich portion. With the in vitro system, radioactivity was detected in insoluble fibrous collagen in the heart valve. The effect of several chelating agents on collagen biosynthesis was studied. BAL, neocuproine, and a,a′-dipyridyl inhibited collagen biosynthesis completely at high concentrations (10−3, m ). On the other hand, EDTA and semicarbazide had very little effect.