Lung carcinoma of sheep (Jaagsiekte). analysis of free amino acids and glucose tolerance tests

Data were collected during a 2½-year follow-up of sheep selected and isolated from a multiple-case herd with lung carcinoma. Eighteen animals were hypergammaglobulinemic for prolonged periods, and 3 of the sheep proved to carry the disease. On forced or deliberate postmortem examination, the other sheep demonstrated various chronic lung diseases with different degrees of severity. One offspring of the selected ewes showed 2 foci of lung carcinoma. The 3 ewes with lung carcinoma had diabetic (2) or slightly diabetic (1) glucose tolerance curves, as compared to normal sheep (case-free herd) of the same age and sex. There were 3 animals free of lung carcinoma, but with chronic lung disease or liver abscesses, that had also diabetic curves. An age-dependent pattern of glucose tolerance curve was obtained. Analysis of free amino acids in the lung revealed a marked decrease in glycine level in the tumor when compared to adjacent lung tissue from the same animal or to normal lung obtained from healthy sheep. Plasma glycine (as well as other amino acids) was decreased in the tumor-bearing animals. Glycine contributed about 25-30% of total plasma amino acids in sheep; alterations in glycine concentration determined in this study were thus quantitative. In lung carcinoma of sheep, glycine offered extensive use as a precursor of nucleic acids (purines), glycogen, and lecithin (a constituent of lung surfactant), the synthesis of all of which was increased in the tumor tissue as compared to normal lung tissue.