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Background and AimsResearch has increasingly suggested that gut flora plays an important role in the development of post-infectious irritable bowel syndrome (PI-IBS). Studies of the curative effect of probiotics for IBS have usually been positive but not always. However, the differences of treatment effects and mechanisms among probiotic stains, or mixture of them, are not clear. In this study, we compared the effects of different probiotics (Befidobacterium, Lactobacillus, Streptococcus or mixture of the three) on intestinal sensation, barrier function and intestinal immunity in PI-IBS mouse model.MethodsPI-IBS model was induced by Trichinella spiralis infection in mice. Different probiotics were administered to mice after 8 weeks infection. Visceral sensitivity was measured by scores of abdominal withdrawal reflex (AWR) and the threshold intensity of colorectal distention. Colonic smooth muscle contractile response was assessed by contraction of the longitudinal muscle strips. Plasma diamine oxidase (DAO) and d-lactate were determined by an enzymatic spectrophotometry. Expression of tight junction proteins and cytokines in ileum were measured by Western blotting.ResultsCompared to control mice, PI-IBS mice treated either alone with Befidobacterium or Lactobacillus (but not Streptococcus), or the mixture of the three exhibited not only decreased AWR score and contractile response, but also reduced plasma DAO and D-lactate. These probiotic treatments also suppressed the expression of proinflammatory cytokine IL-6 and IL-17 and promoted the expression of major tight junction proteins claudin-1 and occludin. The mixture of the three probiotic strains performed better than the individual in up-regulating these tight junction proteins and suppressing IL-17 expression.Conclusions Bifidobacterium and Lactobacillus, but not Streptococcus, alleviated visceral hypersensitivity and recovered intestinal barrier function as well as inflammation in PI-IBS mouse model, which correlated with an increase of major tight junction proteins. In addition, Mixture of three species was indicated to be superior to a single one.

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Recent studies on alkaline soils of arid areas suggest a possible contribution of abiotic exchange to soil CO 2 flux (F c ). However, both the overall contribution of abiotic CO 2 exchange and its drivers remain unknown. Here we analyzed the environmental variables suggested as possible drivers by previous studies and constructed a function of these variables to model the contribution of abiotic exchange to F c in alkaline soils of arid areas. An automated flux system was employed to measure F c in the Manas River Basin of Xinjiang Uygur autonomous region, China. Soil pH, soil temperature at 0-5 cm (T s ), soil volumetric water content at 0-5 cm (θ s ) and air temperature at 10 cm above the soil surface (T as ) were simultaneously analyzed. Results highlight reduced sensitivity of F c to T s and good prediction of F c by the model F c =R 10 Q 10 (Tas-10)/10 +r 7 q 7(pH-7) +λT as +µθ s +e which represents F c as a sum of biotic and abiotic components. This presents an approximate method to quantify the contribution of soil abiotic CO 2 exchange to F c in alkaline soils of arid areas.

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