Background: Chronic use of sennoside laxatives often causes pseudomelanosis coli. A recent study suggested that pseudomelanosis coli is associated with an increased colorectal cancer risk. A single high dose of highly purified senna extract increased proliferation rate and reduced crypt length in the sigmoid colon compared to historical controls. Aims: To evaluate in a controlled study the effects of highly purified senna extract on cell proliferation and crypt length in the entire colon and on p53 and bcl-2 expression. Methods: Addition of a senna extract to colonic lavage was studied in 184 consecutive outpatients. From 32 randomised patients, 15 with sennosides (Sen), 17 without (NSen), biopsies were taken. Proliferative activity was studied in 4 areas of the colon, using 5-bromo-2′-deoxyuridine labelling and immunohistochemistry (labelling index, LI). Expression of p53 and bcl-2 in the sigmoid colon was determined immunohistochemically. Results: Crypts were shorter in Sen than in NSen in the transverse and sigmoid colon. LI was higher in Sen than in NSen in the entire colon. No difference in p53 expression was seen. Bcl-2 expression was higher in both groups when crypts were shorter and/or proliferation was increased. Conclusion: Sennosides induce acute massive cell loss probably by apoptosis, causing shorter crypts, and increased cell proliferation and inhibition of apoptosis to restore cellularity. These effects may reflect the mechanism for the suggested cancer-promoting effect of chronic sennoside use.

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THE development of a tumour can be taken as an expression of a disturbed equilibrium between the number of undifferentiated and differentiated cells of a tissue, in favour of the number of undifferentiated cells. Irrespective of the cause of this disorder, the derailed cells can show morphological, biochemical and immunological deviations. The purpose of this investigation was to compare the histochemical and enzyme histochemical pattern of cells of regenerating bone tissue and of cells of induced bone tumours. To determine the enzyme pattern of cells in regenerating bone tissue healing fractures have been studied. Several methods of inducing bone tumours are known: Radioactive compounds such as 45Ca, 89Sr, 90Sr, 239Pu and 226Ra (Anderson,

The histochemical pattern of the human testes has been investigated. Steroid-producing Leydig cells are characterized by the enzymes 3β ol-hydroxysteroid dehydrogenase and secondary alcohol dehydrogenase. The presence of the last mentioned enzyme precedes that of the 3β ol-hydroxysteroid dehydrogenase. Fibroblast-like interstitial cells showed only enzyme activity of the secondary alcohol dehydrogenase. The best results for indicating the presence of the enzyme 3β ol-hydroxysteroid dehydrogenase were obtained by the method of Allen (1960) with the substrate androst-4-ene-3β,17β-diol. No activity of 3β ol-hydroxysteroid dehydrogenase and the secondary alcohol dehydrogenase was found in the Sertoli cells.