Ethanol-induced alterations in rat hepatic ammonia metabolism

Inhibition of intracellular protein degradation by ethanol in perfused rat liver

Ethanol (50 mM) inhibited proteolysis in the perfused rat liver during stringent amino acid deprivation and also in the presence of normal and 10 times normal concentrations of plasma amino acids. The concentration-response curve of ethanol reached a plateau after 5 mM in both the presence and the absence of normal plasma amino acids, suggesting inhibition by oxidation products of ethanol. Intracellular glutamine, tyrosine and proline increased in concentration with ethanol, but the increases were too small to explain the observed inhibition of proteolysis. The uptake of 125I-asialofetuin was slightly decreased and the output of ammonia increased in the presence of ethanol. These, together with a significant suppression of basal proteolysis in the presence of amino acids, suggest that lysosomal function was directly affected. Electron-microscopic examination of lysosomal components showed that the aggregate volume of autophagosomes (initial vacuoles) were significantly smaller in livers perfused with ethanol than in controls. However, the equivalent volume of autolysosomes (degradative vacuoles) was the same in both groups. According to these results, ethanol inhibits protein degradation in the liver by two discrete mechanisms: one decreasing the formation of autophagic vacuoles and the other involving lysosomotropic inhibition, possibly via ammonia.

Anti-peptide antibodies detect oncogene-related proteins in urine

Antisera to a number of synthetic peptides predicted from nucleic acid sequences of oncogenes have been used to screen 483 urine samples of cancer patients, pregnant women, and normal controls for the presence of immunologically related proteins. Increased levels of oncogene-related proteins are found during neoplasia and pregnancy. The differential detection of these oncogene-related proteins indicates that panels of monoclonal antibodies may provide a convenient noninvasive means of detecting, classifying, and staging a wide variety of malignancies and may be useful in following fetal development during pregnancy.

Renal ammonia metabolic response in the rat to repeated ethanol loading

Lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), aspartate aminotransferase (AAT), glutamate dehydrogenase (GDH), AMP deaminase, ornithine transcarbamylase (OTC), arginase and glutamine synthetase (GS) activities were increased in the kidney of the rat during repeated ethanol loading. The significance of these findings is discussed.

Metabolic fate of ammonia in the rat after ethanol loading

Repeated ethanol loading i.p. produced significant changes in ammonia concentration of different tissues in the rat despite increased levels of urea and glutamine in muscle, kidney and heart.