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Title: Somatomedin inhibitors from the serum of diabetic rats: Effects on mouse embryos in whole embryo culture

Thesis/Dissertation ·
OSTI ID:5405167

Somatomedin inhibitors (SIs) are elevated in the serum of diabetic rats and in human sera during certain disease states, suggesting that serum from human diabetes similarly has enhanced SI activity. A serum fraction of M{sub r} = 800-1080 daltons obtained from diabetic rats and possessing SI activity, was added to the medium used to grow mouse conceptuses in whole embryo culture. Low concentrations of this SI caused malformations in embryos while their visceral yolk sacs (VYSs) were opaque and contained large vacuoles (vesicles) within the endoderm cells. DNA content and the incorporation of {sup 3}H-thymidine into DNA was reduced in both the embryo and its VYS. Concomitantly, the protein content of the embryo was decreased while that of the VYS was increased. Evidence from a variety of experiments indicted that the excess protein in the VYS was not due to de novo protein synthesis but to its sequestering of serum proteins. The failure of the normal VYS function of protein degradation was not due to an inhibition of the lysosomal enzyme, cathepsin B, indicating that some other aspect of protein degradation was affected by the presence of the SI.

Research Organization:
North Carolina Univ., Chapel Hill, NC (USA)
OSTI ID:
5405167
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English