Taking a Step Back: Insights into the Mechanisms Regulating Gut Epithelial Dedifferentiation

Despite the environmental constraints imposed upon the intestinal epithelium, this tissue must perform essential functions such as nutrient absorption and hormonal regulation, while also acting as a critical barrier to the outside world. These functions depend on a variety of specialized cell types that are constantly renewed by a rapidly proliferating population of intestinal stem cells (ISCs) residing at the base of the crypts of Lieberkühn. The niche components and signals regulating crypt morphogenesis and maintenance of homeostatic ISCs have been intensely studied over the last decades. Increasingly, however, researchers are turning their attention to unraveling the mechanisms driving gut epithelial regeneration due to physical damage or infection. It is now well established that injury to the gut barrier triggers major cell fate changes, demonstrating the highly plastic nature of the gut epithelium. In particular, lineage tracing and transcriptional profiling experiments have uncovered several injury-induced stem-cell populations and molecular markers of the regenerative state. Despite the progress achieved in recent years, several questions remain unresolved, particularly regarding the mechanisms driving dedifferentiation of the gut epithelium. In this review, we summarize the latest studies, primarily from murine models, that define the regenerative processes governing the gut epithelium and discuss areas that will require more in-depth investigation

Selenium supplementation and premature (pre-labour) rupture of membranes: a randomised double-blind placebo-controlled trial

The aim was to determine if selenium supplementation during pregnancy reduces the occurrence of premature (pre-labour) rupture of membranes (PROM). A total of 166 primigravid pregnant women in the first trimester of pregnancy, were randomised to receive 100 mg of selenium (n = 83, drop-outs = 22) or a placebo (n = 83, drop-outs = 19) per day until delivery. The incidence of PROM, as well as serum selenium concentrations were evaluated at baseline and at the end of the study. Supplementation with selenium was associated with a significant increase in mean serum selenium concentration at term (p 0.05). The incidence of PROM was significantly lower in the selenium group (n = 8, 13.1%) than in the control group (n = 22, 34.4%) (p < 0.01). Our findings indicate that selenium supplementation (100 mu g/day) in pregnant women effectively reduces the incidence of PRO

Prooxidant-antioxidant balance in pregnancy: a randomized double-blind placebo-controlled trial of selenium supplementation

OBJECTIVE We assessed the impact of selenium, a trace element with antioxidant properties on a simple measure of oxidative stress in pregnant women. STUDY DESIGN A novel assay of prooxidant-antioxidant balance (PAB) was applied in a double-blind, placebo-controlled study of selenium supplementation in pregnancy. We measured the prooxidant burden and the antioxidant capacity simultaneously in one assay, thereby calculating a redox index. A total of 166 primigravid pregnant women in the first trimester of pregnancy, were randomized to receive 100 microg of selenium (n=83) or placebo (n=83) per day until delivery. PAB values and serum selenium concentrations were measured at baseline and at the end of study. RESULTS Pretreatment demographic data and biochemical indices including serum selenium concentrations did not differ significantly between the groups. The drop-out rates for the groups were 22/83 and 19/83 for the selenium and placebo groups, respectively. Supplementation with selenium was associated with a significant increase in mean serum selenium concentration (P<0.001) but without significant change in mean PAB value. In contrast, mean serum selenium concentration remained unchanged and mean PAB values increased significantly (P<0.05 in the control group). CONCLUSION Our findings suggest that selenium supplementation may reduce oxidative stress associated with pregnanc