Low-digestible carbohydrates represent a class of enzyme-resistant saccharides that have specific effects on the human gastrointestinal tract. In the small bowel, they affect nutrient digestion and absorption, glucose and lipid metabolism and protect against known risk factors of cardiovascular disease. In the colon they are mainly degraded by anaerobic bacteria in a process called fermentation. As a consequence, faecal nitrogen excretion is enhanced, which is used clinically to prevent or treat hepatic encephalopathy. Low-digestible carbohydrates are trophic to the epithelia of the ileum and colon, which helps to avoid bacterial translocation. Short-chain fatty acids are important fermentation products and are evaluated as new therapeutics in acute colitis. They are considered in the primary prevention of colorectal cancer. The bifidogenic effect of fructo-oligosaccharides merits further attention. Unfermented carbohydrates increase faecal bulk and play a role in the treatment of chronic functional constipation, symptomatic diverticulosis and, possibly, the irritable bowel syndrome. In conclusion, low-digestible carbohydrates may play a role in the maintenance of human digestive health. However, the strength of evidence differs between disease entities.

Background and aims: Microsatellite instability (MSI) is characterized by the size variation of microsatellites in tumor DNA as compared to matching normal DNA due to defects in the mismatch repair system. To examine the chromosomal differences in microsatellite-stable (MSS) and -unstable (MSI) tumors in detail, we analyzed MSS (Caco-2, Colo-205, SW948) and MSI (HCT-15, HCT-116, LoVo) cell lines by spectral karyotyping (SKY). Methods: SKY is a sensitive method to detect chromosome aberrations by visualizing each chromosome in a different color. Metaphases were hybridized with a SKY probe mixture. Images were visualized with the SpectraCube system and analyzed with the SKYview imaging software. Results: The average number of chromosomes was 49 in LoVo, 45 in HCT-116, 46 in HCT-15, 71 in Colo-205, 89 in Caco-2 and 66 in SW-948. Three aberrant chromosomes were detected in LoVo, three in HCT-116, two in HCT-15, seventeen in Colo-205, fourteen in Caco-2 and nine in SW948. Conclusion: The karyotypes of MSS colon cancer cells displayed complex numerical and structural aberrations. In contrast the chromosomes of MSI colon cancer cells were mostly unaltered but displayed a few isolated numerical and structural aberrations. We speculate that these isolated aberrations may be specifically involved in the pathogenesis of MSI tumors.

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