大鼠烧伤后肠粘膜上皮细胞凋亡及其相关调控因子变化的研究

目的探讨大鼠烧伤后肠粘膜上皮细胞凋亡情况及相关调控因子变化的关系.方法 Wistar大鼠按随机数字表法分为烧伤组与正常对照组.动物于伤后6、12 h、1、3、5 d处死,流式细胞仪检测肠粘膜上皮细胞凋亡数,TUNEL法检测细胞凋亡形态学变化,RT-PCR法检测肠粘膜bcl-2 mRNA表达的变化,荧光法检测肠上皮细胞caspase-3酶活性.结果烧伤后6 h至5 d肠上皮凋亡细胞数较正常组明显增加;TUNNEL检测显示:烧伤后6 h阳性细胞数较正常组即有增加,伤后1 d表达最强,以后稍有减弱,但仍强于伤前;肠粘膜bcl-2 mRNA表达在伤后12 h开始低于正常,至伤后5 d仍低于正常,烧伤后大鼠肠上皮细胞caspase-3的活性在伤后1 d明显升高,伤后3 d到峰值,然后迅速下降至正常范围内.caspase-3活性变化与细胞凋亡数呈显著的正相关(r=0.56,P<0.05);烧伤后bcl-2 mRNA的表达与细胞凋亡数呈显著负相关(r=-0.72,P<0.05).结论烧伤后肠粘膜上皮细胞凋亡增加,尤以伤后1、3 d最为明显, caspase-3,bcl-2参与了烧伤后肠粘膜上皮细胞凋亡的调控.     

烧伤早期肠道喂(营)养的几个问题

提出了早期肠道喂养与营养的含义、共同点及不同点。烧伤早期肠道喂（营养）可维护肠道结构、功能、降低伤后高代谢。早期肠道喂（营养）的机制至少有三；（１）减轻肠道损伤，改善胃肠道血流，减轻缺血再灌注损伤；（２）减少肠道内毒素移位，调理枯否细胞活化；（３）降低体内介质、激素水平。     

γ干扰素与肿瘤坏死因子α对肠上皮屏障功能影响的实验研究

Objective To investigate the effect of combination of interferon-gamma (IFN-γ) and tumor necrosis factor-alpha ( TNF-α ) on intestinal epithelial barrier function. Methods The Caco-2 monolayers were cultured in DMEM nutrient solution, and then they were inoculated in 24-well or 6-well plate with Transwell inserts. They were divided into control group ( ordinary treatment), IFN-γ group ( with addition of 10 ng/mL IFN-γ), TNF-α group (with addition of 10 ng/mL TNF-α), and IFN-γ plus TNF-α group (with addition of 10 ng/mL TNF-α and 10 ng/mL IFN-γ ). Monolayers inoculated in 24-well plate were collected for determination of transepithelial electrical resistance (TER) with an ohmmeter at post treatment hour (PTH) 0, 6, 12, 24, 36, and 48, the permeability of monolayers with fluorescein isothiocyahate-labeled dextran (FITC-dextran) tracer method at PTH 48, the distribution and morphological change of tight junction occludin with immunofluorescence assay at PTH 48. Monolayers inoculated in 6-well plate were collected for determination of protein expression of occludin, myosin light chain kinase (MLCK), and phosphorylated MLC (pMLC) with Western blot at PTH 24. Data were processed with one-way analysis of vaiiance and t test. Results ( 1 ) There was no obvious difference in TER in control group at each time point ( F = 0. 86, P ＞ 0.05 ). TER in IFN-γgroup and TNF-α group were gradually decreased during PTH 6-48,but showed no statistical difference as compared with that at PTH 0 ( with F value respectively 1.69, 2.47,P values all above 0.05 ). TER in IFN-γplus TNF-α group was significantly decreased from PTH 24 as compared with that at PTH0 ( t =4.97, P ＜0.05) and that in each of the other three groups ( F =11.54,P ＜ 0.05 ). (2) The permeability of monolayers in IFN-γplus TNF-α group [( 1197 ± 215 ) pmol] was significantly higher than that in control group, IFN-γ group, and TNF-α group [( 303 ± 93 ), ( 328 ± 76),(797 ± 177) pmol, with t value respectively 4.8, 5.0, 6.9, P values all below 0.01]. (3) There was no statistical difference in occludin expression at PTH 24 among four groups ( F = 0.26, P ＞ 0.05). The occludin in control group at PTH 48 was regular in arrangement, while that in IFN-γand TNF-α groups was irregular in arrangement. The arrangement of occludin in IFN-γ plus TNF-c group at PTH 48 was interrupted,with obvious redistribution in cytoplasm. (4) The protein expression of pMLC in IFN-γ plus TNF-α group (0.95 ±0.05) was significantly higher than that in control group, IFN-γ group, or TNF-α group (0.57 ±0.12, 0.56 ±0.07, 0.59 ±0. 10, respectively, F = 17.97, P ＜0.01). The protein expression of MLCK in IFN-γplus TNF-α group (1.57 ±0.36) was also significantly higher than that in control, IFN-γ, TNF-α groups (0.85 ± 0.18, 1.04 ± 0. 23, 1.00 ± 0.07, respectively, F = 9.05, P ＜ 0.05 ). Conclusions Combination of IFN-γand TNF-α can induce intestinal epithelial barrier dysfunction by up-regulating MLCK protein expression and promoting MLC phosphorylation.     

严重烧伤后肠黏膜肌球蛋白轻链磷酸化表达改变及其意义

目的探讨肌球蛋白轻链（myosin light chain,MLC）磷酸化在严重烧伤早期对肠黏膜屏障功能及细胞紧密连接相关蛋白变化的作用。方法健康成年SD大鼠48只,采用随机数字表法分为正常对照组及烧伤后1、2、6、12、24h组,用异硫氰酸荧光素．葡聚糖（FITC-Dextran）检测大鼠肠黏膜通透性,免疫荧光法检测肠黏膜细胞紧密连接相关蛋白ZO-1、F-肌动蛋白（F．actin）及磷酸化型MLC（phosphorylated MLC,p-MLC）的变化。结果烧伤后大鼠肠黏膜通透性明显增加,伤后6h达高峰,为对照组的3倍（P〈0．01）;烧伤后肠上皮通透性的增加伴随有紧密连接相关蛋白ZO-1的明显重分布、细胞紧密连接损害以及肠上皮细胞p-MLC表达的增加。结论MLC磷酸化可能在严重烧伤后肠黏膜屏障功能紊乱及通透性增加的发生机制中起着重要的调控作用。     

非编码RNA在结直肠癌早期诊断中的应用

非编码RNA(ncRNA)是一类不具有编码蛋白质功能的RNA。近年来越来越多的研究结果显示结直肠癌(CRC)的发生发展与ncRNA的异常表达密切相关,可作为一种无创性检测生物标志物用于CRC的早期诊断。对目前ncRNA在CRC早期诊断中的研究进展进行综述,总结ncRNA检测的潜在临床价值,可为提高CRC的早期诊断率提供...