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- Albèr, Cathrine, et al.
(författare)
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Effects of water activity and low molecular weight humectants on skin permeability and hydration dynamics : a double-blind, randomized and controlled study
- 2014
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Ingår i: International Journal of Cosmetic Science. - : John Wiley & Sons. - 0142-5463 .- 1468-2494. ; 36:5, s. 412-418
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The mammalian skin is a barrier that effectively separates the water-rich interior of the body from the normally dryer exterior. Changes in the external conditions, for example ambient humidity, have been shown to affect the skin barrier properties. The prime objective of this study was to evaluate the effect of water activity of a topical formulation on skin hydration and permeability. A second objective was to gain more understanding on how two commonly used humectants, urea and glycerol, affect skin barrier function in vivo. METHODS: Simple aqueous formulations were applied under occlusion to the volar forearm of healthy volunteers. Following 4-h exposure, skin water loss (by transepidermal water loss measurements), skin hydration (by Corneometry) and skin permeability (by time to vasodilation due to benzyl nicotinate exposure) were monitored. RESULTS: The results demonstrate that a relatively small change in the water activity of a topical formulation is sufficient to induce considerable effects on stratum corneum hydration and permeability to exogenous substances. Exposing the skin to high water activity leads to increased skin hydration and also increased permeability. Furthermore, urea and glycerol promote skin hydration and permeability even at reduced water activity of the applied formulation. CONCLUSION: These results highlight the importance of considering the water activity in topically applied formulations and the potential benefit of using humectants. The results may impact formulation optimization in how to facilitate skin hydration and to modify skin permeability by temporarily open and close the skin barrier.
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- Midtvedt, Tore, et al.
(författare)
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Increase of faecal tryptic activity relates to changes in the intestinal microbiome : analysis of Crohn's disease with a multidisciplinary platform.
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:6, s. e66074-
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate-by molecular, classical and functional methods-the microbiota in biopsies and faeces from patients with active Crohn's disease (CD) and controls.DESIGN: The microbiota in biopsies was investigated utilizing a novel molecular method and classical cultivation technology. Faecal samples were investigated by classical technology and four functional methods, reflecting alterations in short chain fatty acids pattern, conversion of cholesterol and bilirubin and inactivation of trypsin.RESULTS: By molecular methods we found more than 92% similarity in the microbiota on the biopsies from the two groups. However, 4.6% of microbes found in controls were lacking in CD patients. Furthermore, NotI representation libraries demonstrate two different clusters representing CD patients and controls, respectively. Utilizing conventional technology, Bacteroides (alt. Parabacteroides) was less frequently detected in the biopsies from CD patients than from controls. A similar reduction in the number of Bacteroides was found in faecal samples. Bacteroides is the only group of bacteria known to be able to inactivate pancreatic trypsin. Faecal tryptic activity was high in CD patients, and inversely correlated to the levels of Bacteroides.CONCLUSIONS: CD patients have compositional and functional alterations in their intestinal microbiota, in line with the global description hypothesis rather than the candidate microorganism theory. The most striking functional difference was high amount of faecal tryptic activity in CD patients, inversely correlated to the levels of Bacteroides in faeces.
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