Effect of riboflavine deficiency on nucleic acid metabolism of liver in the rat

1. The effect of riboflavine deficiency on liver ribonuclease activity, RNA and DNA content, and32P incorporation into RNA and DNA has been studied in rats maintained on a 16% protein diet, a protein-free diet and on a protein-free diet subsequently replaced with a 40% protein diet.

2. Rats maintained on a riboflavine-deficient diet for 45 days showed decreased incorporation of32P into liver RNA but no effect on the RNA content of liver. The concentration of DNA in liver and33P incorporation into it remained unaffected. After a deficiency period of 70 days, both the RNA and DNA contents of liver were found to be decreased. When the riboflavine-deficient or control rats were given the protein diet for 30 days and then a proteinfree diet for 15 days, the RNA content of their livers decreased, while the liver DNA content was increased. Repletion with a 40% protein diet restored the RNA and DNA content in both control and riboflavine-deficient rats.

3. Liver ribonuclease activity was decreased after a deficiency period of 45 days, whereas it was increased after a deficiency period of 70 days.

4. A correlation between liver RNA level and liver ribonuclease activity in riboflavine deficiency is suggested.

Proteolytic enzymes of human intestinal mucosa in non-malignant diseases of the ileum and colon

Preparations of mucosal epithelium were made from 10 samples of normal colon, 10 of normal ileum, 20 from colon involved by ulcerative colitis, 10 from ileum affected by regional ileitis, 4 from colon resected for diverticulitis, 2 from megacolon, and 2 from colonic polyps. The activity of proteolytic enzymes using haemoglobin as substrate and tissue nitrogen as reference was measured at pH 3·75 and pH 6·50 in homogenates, supernatants and particulate preparations before and after treatment with detergent.

In normal colon and ileum, proteolytic activity at pH 3·75 was of similar magnitude and was mainly soluble; activity at pH 6·50 was greater in ileum, and in both tissues was mainly associated with particulate fractions.

Samples involved by ulcerative colitis gave lower activities in all fractions at both pH values, the extent of the reduction being related to the severity of the disease. No evidence for a lysosomal defect was obtained.

Samples affected by regional ileitis did not differ from normal ileum in proteolytic activity at pH 3·75, but values at pH 6·50 tended to be lower. At both pH values, a higher percentage of the total activity was soluble prior to treatment with detergent which solubilised little additional enzyme; this may indicate a lysosomal defect.

Diverticulitis samples had lower activity at pH 3·75, but did not differ from normal colon at pH 6·50. No striking abnormalities were noted in megacolon or colonic polyps.

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Sigmoidoscopic and radiological study of the recto-sigmoid junction

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