Chronic ingestion of environmental heavy metals such as lead (Pb) and cadmium (Cd) causes various well-documented pathologies in specific target organs following their intestinal absorption and subsequent accumulation. However, little is known about the direct impact of the non-absorbed heavy metals on the small intestine and the colon homeostasis. The aim of our study was to compare the specific bioaccumulation and retention of Cd and Pb and their effect on the essential metal balance in primary organs, with those occurring specifically in the gastrointestinal tract of mice. Various doses of Cd (5, 20 and 100 mg l(-1)) and Pb (100 and 500 mg l(-1)) chloride salts were provided in drinking water for subchronic to chronic exposures (4, 8 and 12 weeks). In contrast to a clear dose- and time-dependent accumulation in target organs, results showed that intestines are poor accumulators for Cd and Pb. Notwithstanding, changes in gene expression of representative intestinal markers revealed that the transport-, oxidative- and inflammatory status of the gut epithelium of the duodenum, ileum and colon were specifically affected by both heavy metal species. Additionally, in vivo comet assay used to evaluate the impact of heavy metals on DNA damage showed clear genotoxic activities of Cd, on both the upper and distal parts of the gastrointestinal tract. Altogether, these results outline the resilience of the gut which balances the various effects of chronic Cd and Pb in the intestinal mucosa. Collectively, it provides useful information for the risk assessment of heavy metals in gut homeostasis and further disease's susceptibility.

Background: Hyaluronic acid (HA), both crosslinked and uncrosslinked, is used clinically to treat fine lines and provides additional improvements in skin quality attributes. The purpose of this study was to assess potential early differences in the expression of biological markers of skin quality in living human skin explants injected with uncrosslinked and crosslinked HA gels. Methods: Living human skin explants injected with VYC-12L or noncrosslinked HA with mannitol (HYD) and noninjected controls were assessed via microscopy, histology, and immunohistochemistry on days 3 and/or 8 for biological markers of elasticity (collagen density, elastin, fibrillin-1) and hydration [aquaporin-3, acidic glycosaminoglycans (GAGs), HA]. Hydration was also assessed via a corneometer probe on days 0, 1, 2, and 8. Results: On day 3 versus controls, VYC-12L moderately increased collagen density in the upper reticular dermis and clearly increased fibrillin-1 expression, with slight increases persisting on day 8. Increases with HYD were smaller and did not persist on day 8. Both VYC-12L and HYD increased aquaporin-3 expression and GAG content on days 3 and 8, but VYC-12L produced greater GAG increases in the reticular dermis. Day 8 instrument-assessed hydration increased by 49% and 22% for VYC-12L and HYD, respectively. Elastin expression in oxytalan and elaunin fibers was unchanged. Upper-dermal HA reductions suggested HA injection-induced hyaluronidase expression. Conclusion: VYC-12L produced greater, more lasting improvements in biological markers of skin quality than HYD.

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