A New Rat Model of Pouchitis After Proctocolectomy and Ileal Pouch-Anal Anastomosis Using 2,4,6-Trinitrobenzene Sulfonic Acid.

BACKGROUND: Pouchitis is a common complication after ileal pouch-anal anastomosis (IPAA) in patients with ulcerative colitis. However, an ideal model remains lacking. Therefore, we aimed to establish an appropriate model resembling human pouchitis. METHODS: Sprague-Dawley rats were randomly assigned to five groups: TNBS group, DSS group, NS group (following IPAA procedure, administrated with TNBS enema, DSS orally, normal saline enema, respectively), NI group (underwent IPAA), and sham group (underwent switch abdominal surgery). General status, weight change, hematochezia, and fecal scores were recorded. Fecal microbiota were counted under a microscope and analyzed by 16S rRNA gene high-throughput sequencing. Specimens of ileal pouch and small intestine (proximal, mid, distal) were collected to evaluate myeloperoxidase and occludin expression by immunohistochemistry and mRNA expression of pro-inflammatory markers by PCR. RESULTS: General status, hematochezia, fecal score, and increased mRNA expression of interleukin-6 and TNF-α in the TNBS group were similar to those in the DSS group, whereas the TNBS-induced model displayed a more stable weight change and more serious dysbacteriosis, not only was fecal bacterial diversity reduced, the dominant microbiota was altered. Histopathology scores of the distal small intestine in the TNBS group were lower compared with those in the DSS group (P < 0.05). A significant difference in myeloperoxidase and occludin expression in the small intestine was also detected between the TNBS and DSS groups. CONCLUSIONS: Our model mimicked the characteristics of human pouchitis and avoided potential side effects in the small intestine, and thus could be employed for further research.

[Characteristics of soil aggregates and inorganic phosphorus fractions in soils returned from cropland to tea]. / é€€è€•æ¤èŒ¶åœ°åœŸå£¤å›¢èšä½“åŠå ¶æ— æœºç£·ç»„åˆ†åˆ†å¸ƒç‰¹å¾.

With soils returned from cropland to tea planting for different ages (2-3, 9-10 and 16-17 years old) as the object, and the nearby cropland soil as the control in Zhongfeng Township, Mingshan County, Ya'an, Sichuan Province, field investigation and laboratory analysis were combined to investigate the characteristics of soil aggregates and inorganic phosphorus fractions in response to the returning from cropland to tea. The particle size of >2 mm was the dominant aggregate size for the cropland and tea soils. With the increasing age, soil aggregate content of >5 mm particle size increased, while that of <5 mm particle size decreased gradually. In the earlier ages, for the mean mass diameter (MWD) and the geometry mass diameter (GWD), there was no significant difference between the cropland and tea soils. The MWD and GMD for the tea soils of 9-10 years and 16-17 years increased with the increasing age and were higher than those of the control. Compared with the cropland, the tea soils showed higher contents of Al-P and Fe-P, and lower content of O-P. The content of O-P in different particle size of aggregates reduced with the increasing age, while that of Al-P and Fe-P increased with the increasing age. The contents of Al-P and Ca-P in the cropland and tea soils increased with the decrease of the particle size and reached the maximum value in the particle size of <0.25 mm. The highest content of Fe-P was observed in the particle size of <0.25 mm, followed by 2-5 mm and 0.25-0.5 mm. Besides, with the returning fromcropland to tea planting, O-P gradually accumulated in smaller particle size and possessed higher content in the particle size of <2 mm.

[Ecological stoichiometry of soil carbon, nitrogen and phosphorus within soil aggregates in tea plantations with different ages].

This study selected 4 tea plantations with different ages (12-15, 20-22, 30-33 and >50 year-old) located in Ya' an, Sichuan Province, China to investigate the distribution patterns of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) , and to examine the ecological stoichiometric characteristics of C, N and P within soil aggregates. The results showed that the coefficients of variation of SOC, TN and TP were 17.5%, 16.3% and 9.4%, respectively in the 0-20 cm soil layer and were 24.0%, 21.0% and 9.2%, respectively in the 20-40 cm soil layer. The spatial variation of TP was lower than that of SOC and TN but there were significant positive correlations among them. SOC and TN were distributed in the small-size aggregates and both of them had the greatest values in the >50 year-old tea plantation, however, the distribution of TP was relatively uniform among aggregates and ages. The coefficients of variation of C/N, C/P, and N/P were 9.4%, 14.0% and 14.9%, respectively in the 0-20 cm soil layer and were 7.4%, 24.9% and 21.8%, respectively in the 20-40 cm soil layer. Variation of C/N was lower than that of C/P and N/P. Averaged C/P and N/P values in the small-size aggregates were higher than in aggregates of other sizes, and the maximum values were in the >50 year-old plantation. C/N, C/P and N/P had good indication for soil organic carbon storage.

[Characteristics of distribution and transportation of rice genotype with high nitrogen utilization efficiency at the late growth stage].

Taking a high nitrogen utilization efficiency rice genotype (NUE(H)) as test material and a low nitrogen utilization efficiency genotype (NUE(L)) as control, a pot experiment was carried out with nitrogen treatments of 100 (low) and 200 mg x kg(-1) (normal), to analyze the differences in nitrogen accumulation distribution, translocation and transport efficiency between the two genotypes. The results showed that NUE(H) could still maintain a high yield and a high nitrogen utilization efficiency at the low rate of nitrogen fertilization, with the grain yield being 1.75 times of that of NUE(L), and the nitrogen recovery efficiency of 50.9% compared with 36.4% for NUE(L). Compared to the normal nitrogen fertilization rate, the low nitrogen fertilization rate promoted the nitrogen accumulation by 34.2%, 2.5% and 0.5% in NUE(H) at the flowering, filling and mature stages, while decreased by 23.5% and 15.6% in NUE(L) at filling and mature stages, respectively. Nitrogen accumulation distribution in organs of NUE(H) was in the order of leaf > stem > root > spike, spike > leaf > stem > root, and spike > stem > leaf > root at the flowering, filling and mature stages, respectively. With the advancement of growth period, the nitrogen accumulation in spike increased obviously. At the two nitrogen fertilization rates, nitrogen transfer was ordered as leaf > stem > root for NUE(H), and stem > leaf > root for NUE(L), and nitrogen transfer efficiencies of NUE(H) were 50.8%, 60.3%, which were as 1.67 and 1.55 times as that of NUE(L), respectively. It could be concluded that the higher nitrogen transport efficiency of NUE(H) leaves laid a good foundation for the construction of grain after heading.

[Effect of silicon on translocation and morphology distribution of lead in soil-tobacco system].

Taking tobacco as test material, a pot experiment was conducted to study the effect of silicon on translocation of lead (Pb) form soil to tobacco in order to explore effective measures for reducing Pb concentration in tobacco leaf. The results showed that silicon application promoted the transformation of exchangeable Pb into Fe-Mn oxide-bound Pb in non-rhizospheric soil, and into Fe-Mn oxide-bound Pb and residual Pb in rhizospheric soil, which decreased the availability and mobility of Pb in the soil. Silicon application significantly reduced the Pb uptake of tobacco, with the content of Pb being decreased by 6.5% to 44.0% in tobacco, and 3.1% to 60.4% in leaf. Silicon application promoted the transformation of ethanol-extractable, H2O-extractable Pb and NaCl-extractable Pb into HCl-extractable Pb and residual Pb in root, stem and leaf of tobacco, which reduced the toxicity and mobility of Pb in tobacco. Silicon restricted the transportation of Pb from soil to tobacco leaf by reducing the mobility index of Pb from soil to root and the mobility index of Pb from root to stem in soil-tobacco system. Meanwhile, the mobility index of Pb from stem to leaf in soil-tobacco system showed a rising-and-falling trend with the increase of Pb application. Silicon inhibited the Pb migration from soil to tobacco leaf by reducing availability of Pb, mitigating toxicity of Pb to tobacco, and changing the distribution of Pb forms in tobacco, consequently reducing Pb concentration of tobacco leaf. These results demonstrated silicon application could be effective in reducing translocation of Pb from soil to tobacco.