Experimental studies indicate that laxatives may induce epithelial damage. In addition, some laxatives induce the release of prostaglandins. Epithelial cell damage and release of prostaglandins are two pathways by which epithelial cell proliferation could be influenced. Furthermore, fermentable laxatives like lactulose may influence large intestine cell proliferation by the trophic effect of the fermentation products such as short-chain fatty acids. For these reasons an in vivo study in rats was performed to compare the short- and long-term effect of sennosides, bisacodyl, sodium picosulfate and lactulose on epithelial cell proliferation in the ileum and large intestine. Cell proliferation was examined by the BrdUrd labelling technique after 2, 6 and 12 weeks of continuous treatment. Studies in control animals show that the Labeling Index (LI) is higher in the cecum compared with other segments of the colon, and higher in the ileum than in the colon. Treatment with sennosides, bisacodyl and sodium picosulfate does not influence the LI in the ileum and induces no statistically significant increase of the LI when the treated groups are compared with the control group. The proliferative pattern along the crypts remains unchanged with all the laxatives throughout the study. It appears therefore that ‘contact’ laxatives have no major influence on ileal and colonic epithelial cell proliferation and should not be regarded as tumor-promoting substances.
Starting from the study of an architect who designs in the absence of sight, we question to what extent prevailing notions of design may be complemented with alternative articulations. In doing so, we point at the cognitivist understanding of human cognition underlying design researchers' outspoken attention for 'visual thinking', and contrast this with more situated understandings of human cognition. The ontological and epistemological differences between both raise questions about how design research is produced, and consequently what design can also be. By accounting for how a blind architect re-articulates prevailing notions of design, we invite researchers to keep the discussion open and call for an ontological and epistemological re-articulation in design research.
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