Liver enzymes in human undernutrition.

‘The study of nutrition and the study of enzymes represent two sides of the same coin’ (Green, 1946). This statement is specially applicable in cases of nutritional oedema and kwashiorkor, both being states of protein malnutrition. Since enzymes are protein in nature it is to be expected that protein malnutrition will lead to a diminution in the quantity of enzymes. Acute starvation in rats produces a marked reduction of liver nitrogen (Addis, Po0 & Lew, 1936; Campbell & Kosterlitz, 1954; Vars & Gurd, 1947a, b). Campbell & Kosterlitz (1948) showed that the protein content of the liver is directly related to the protein content of the diet; in inanition as well as on a protein-deficient diet the decrease of liver protein follows a steep curve in the first few days and later shows a slow linear decline. They attributed the initial rapid decline to the loss of what they termed ‘labile liver cytoplasm’. Vars (1954) thought the labile liver cytoplasm to be associated with certain enzymic functions, whereas the remaining part is concerned with other enzymic activities. Schultz (1949) described the enzymes readily lost on fasting as ‘labile’. Virtanen & Winkler (1949) divided the liver enzymes into indispensable and dispensable according as they were preserved or lost during dietary restriction. In acute inanition Miller (1948) found in the rat a decrease of liver-catalase, alkaline-phosphatase, xanthine-dehydrogenase and cathepsin activities which paralleled and sometimes exceeded the loss of liver protein. Similarly, Rosenthal, Rogers, Vars & Ferguson (1950) observed a loss of 68 yo in total arginase and rhodanase activities of the rat liver after a fast lasting z weeks. Axelrod & Elvehjem (1941), after producing riboflavin deficiency in rats, found that the protein component of xanthine dehydrogenase formed a sensitive index of protein malnutrition. Bargoni (195 I) showed a remarkable increase of liver alkaline phosphatase in protein malnutrition, whereas esterase, catalase and choline-oxidase activities declined and dipeptidase remained unchanged. Srinivasan & Patwardhan (1955) noted an increase of alkaline phosphatase in malnutrition. But data obtained for animals may not be directly relevant to man. Moreover, most of the animal experiments have been done in acute starvation and the findings obtained in such a condition will, of course, be different from those in chronic prolonged undernutrition, with which we are more specifically concerned. Research on human subjects is difficult, since only one tissue, blood, is readily available. Valuable data have been collected on the changes in blood enzymes in human starvation (Hutchinson, 1951; Hutchinson, McCance & Widdowson, 1951 ; Mukherjee & Chaudhuri, 1957 ; Mukherjee & Werner, 1954). Lately, the relative innocuousness of liver biopsy has been demonstrated. Waterlow (1954) and Waterlow & Patrick (1954) in the West