Urinary excretion of lysosomal arylsulfatases in kwashiorkor

Enzymes and the assessment of protein nutrition

This symposium is concerned with the assessment of protein nutritional status in man. The question we have to examine is whether measurements of enzyme activity are, or may be in the future, of any value for this purpose. There are several concepts which may be useful in considering this problem, such as the nature of enzymes and the regulation of their amount in the body, the effect on activity of a biochemical lesion at the cellular level, and the adaptive changes that reflect an altered balance of metabolic pathways.

Liver lysosomal enzymes in rats during long-term dietary restriction. 1. Changes during the developmental period of life

The specific activities of the lysosomal enzymes acid phosphatase, beta-galactosidase, arylsulphatase B and cathepsin D were determined in homogenates of livers of rats fed ad libitum and of rats subjected to long-term dietary restriction (10%, 30% and 50% of diet consumed by the ad libitum group). Dietary restriction began soon after weaning and animals were sacrificed 3, 9, 15 and 24 weeks later. Dietary restriction influenced all four enzymes but the changes depended on the enzyme as well as on the degree and duration of the dietary restriction. Total activity of acid phosphatase increased significantly at 3 weeks of restriction but only in the 50% group. The activity returned to normal values at 9 weeks. Arylsulphatase B increased in all experimental groups with a more pronounced change observed at 3 weeks and in the more severely restricted rats. No notable change in the activities of beta-galactosidase and cathepsin D activities was observed. Changes in the liver ultrastructure paralleled the biochemical changes seen at 3 weeks. Numerous autophagic vacuoles and dense bodies resembling age pigments were formed in the hepatocytic cytoplasm. Mitochondrial enlargement, increased matrical density and rough endoplasmic reticulum fragmentation were also noted. Few of these changes were observed at 9 weeks, and the hepatocyte's morphology was virtually normal at 15 and 24 weeks. The marked changes seen at 3 weeks may be a manifestation of the body's adaptive processes to the nutritional stress.

Urinary excretion of arylsulfatases in malnourished/vitamin A deficient children

Serum vitamin A (retinol) levels were generally low in all malnourished children (6-15 microgram/100 ml) compared with control children (50 microgram/100 ml). A significant increase in vitamin A after appropriate therapy was observed in all malnourished groups. Dietary supplements of proteins and calories even without extra vitamin A supplements increased serum vitamin A levels in cases of kwashiorkor indicating active mobilization of liver vitamin A. Total urinary arylsulfatase A activity excreted in 24-h or within 8-h in the morning (6 a.m. to 2 p.m.) was significantly reduced in cases of malnutrition with or without mild vitamin A deficiency symptoms. The excretion of arylsulfatase B was not altered. In cases of severe vitamin A deficiency coupled with malnutrition increased excretion of both arylsulfatases A and B was evident. These results on urinary arylsulfatases excretory pattern have been obtained either in samples collected for 24-h or specifically for 8-h (morning) and it is suggested that this test on urinary arylsulfatases may prove useful for detection of acute vitamin A deficiency with malnutrition in field studies. A ratio of arylsulfatases A/B of 2.0 or less seems to indicate mild malnutrition, the normal ratio being 3.4. Furthermore a low ratio coupled with increased excretion of both arylsulfatases A and B may be considered specific for acute vitamin A deficiency.

Changes in lysosomal hydrolase activity associated with malnutrition in young rats

1. Total lysosomal hydrolase activities were measured in liver, gastrocnemius muscle and plasma of malnourished and normal rats between 3 and 8 weeks of age.

2. Concurrently, the DNA and protein contents of the livers and muscles were determined.

3. Increased amounts of acid hydrolase activities were found to be associated with subnormal protein: DNA ratios in the tissues of malnourished rats.

4. It was concluded that lysosomal enzymes may be involved in protein catabolism during malnutrition.

Enzymes and the assessment of protein nutriton

This symposium is concerned with the assessment of protein nutritional status in man. The question we have to examine is whether measurements of enzyme activity are, or may be in the future, of any value for this purpose. There are several concepts which may be useful in considering this problem, such as the nature of enzymes and the regulation of their amount in the body, the effect on activity of a biochemical lesion at the cellular level, and the adaptive changes that reflect an altered balance of metabolic pathways.