The chemical composition and capacity for protein synthesis of the liver of cattle suffering from clinical Johne's disease

Central Veterinary Laboratory, Weybridge Received January 12, 1968 Accepted March 25, 1968 Liver tissue was obtained from 5 cases of clinical Johne's disease by biopsy and analysed for total nitrogen, protein nitrogen, "collagen", lipid, nucleic acids, acid-soluble ribonucleotides and ATP. Comparisons were made with liver tissue from healthy cows. The only significant changes in chemical composition were a small rise in liver lipid content and a marked increase in tissue hydroxyproline, indicating increased connective tissue and suggesting early fibrosis. The in-vitro rate of protein synthesis was assayed in 2 clinical cases and 3 controls by means of the rate of incorporation of [U- 14 C] leucine into the proteins of liver slices. A higher than normal rate of synthesis was observed in the liver tissue from the cows with clinical Johne's disease but, at the same time, tissue concentrations of three enzymes (glucose-6-phosphatase, hexose monophosphate dehydrogenase and lactate dehydrogenase) were lowered.