Extracellular signal-regulated kinase (ERK) activation in chicken heterophils stimulated with phorbol 12-myristate 13-acetate (PMA), Formyl-methionylleucyl-phenylalanine (fMLP) and lipopolysaccharide (LPS)

The signaling pathways leading to the activation of extracellular signal-regulated kinase (ERK) by phorbol 12-myristate 13-acetate (PMA), formyl-methionylleucyl-phenylalanine (fMLP) and lipopolysaccharide (LPS) in chicken heterophils were examined. To determine the mechanism of ERK's activation and its relation with the influx of calcium ions, heterophils were stimulated by PMA, fMLP and LPS. ERK was not activated by fMLP. LPS- and PMA-stimulated activation of ERK, based on Western blotting with antibodies against the phosphorylated form of ERK, was attenuated by the pretreatment of cells with the intracellular calcium chelator BAPTA/AM (1,2-bis (o-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid) but not with the extracellular calcium chelator EGTA (glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid). Exposure of cells to the protein kinase C (PKC) inhibitor GF109203X inhibited the LPS- and PMA-stimulated phosphorylation of ERK in a concentration-dependent manner. The LPS-stimulated phosphorylation was inhibited by pretreatment with the phospholipase C (PLC) inhibitor U73122 but not the phosphatidylinositol 3-kinase (PI₃K) inhibitor LY294002. These results indicate that the LPS-induced phosphorylation of ERK in the chicken heterophils is mediated by PLC, PKC and intracellular calcium, and the PMA-stimulated phosphorylation is dependent on intracellular calcium ion and PKC.     

日粮核苷酸对机体炎症抗炎症平衡体系的影响

为探讨日粮核苷酸对小鼠炎症／抗炎症平衡体系的作用，用CpG DNA和脂多糖（LPS）刺激小鼠构建炎症反应模型，观察分别饲喂无核苷酸（NF）日粮和核苷酸（NT）日粮小鼠的炎性细胞因子IL-1、IFN-λ，、抗炎性细胞因子IL-10水平和小肠髓过氧化物酶（MPO）活性变化。结果显示，在刺激后第4h时，NT组小鼠的IL-1（P〈0．05）、IFN-λ，（P〈0．01）和小肠MPO（P〈0．01）明显低于NF组，IL-10（P〉0．05）高于NF组；刺激后第18h时，NT与NF组的IL-1（P〈0．01）、IFN-λ，（P〈0．01）、IL-10（P〉0．05）和MPO（P〈0．01）均较刺激后第4h有所降低，NT组的IL-1（P〉0．05）、IFN-λ，（P〈0．05）和小肠MPO（P〈0．05）仍低于NF组，IL-10（P〉0．05）仍高于NF组。表明，日粮核苷酸对CpG DNA或LPS所诱导的炎症反应有明显的抑制作用，有助于维持机体炎症／抗炎症平衡，保护机体免受炎症损伤。     

LPS和LT对肠黏膜VEC内分泌NO和ET的影响

研究LPS和LT引起肠黏膜微血管内皮细胞(VEC)损伤的作用机制。将所培养的肠黏膜VEC 60个孔分为空白对照组、LPS(1μg/mL)组和LT(50μg/mL)组3个组,每个组又分4个不同时间段:3h、6h、9h、12h。结果LPS导致肠黏膜VEC分泌NO明显升高,3 h后达到高峰,随后逐渐降低,而ET分泌急剧升高,9 h后达到高峰。LT导致肠黏膜VEC分泌NO明显升高,3 h达到高峰,随后逐渐降低,而ET在6 h前明显降低,随后逐渐升高到正常水平。     

LPS致肝细胞损伤模型的建立研究

[目的]探索LPS体外致人ChangLiver细胞损伤模型的建立方法和意义。[方法]分别用20．40、60、80、1130μg／ml浓度的LPS作用ChangLiVer细胞24h,采用MTF法检测LPS对ChangLivet细胞存活率的影响,分别测定ChangLiver细胞上清中谷草转氨酶（AST）、谷丙转氨酶（ALT）、碱性磷酸酶（ALP）、γ-谷氨酰转肽酶（γ-GT）、乳酸脱氢酶（IJDH）的活性,并通过Hoechst33258荧光染色观察用药24h后ChangLiver细胞形态的变化。[结果]80和100u晷／ml浓度的LPS作用后ChangLiver细胞存活率显著性降低,胞外AST、ALT、ALP、γ-GT、LDH酶活性升高,细胞数目减少,细胞形态发生改变,呈现细胞核固缩等细胞凋亡现象。（结论l用80μg/ml的LPS与ChangLiver细胞共培养24h,可以建立理想的体外肝细胞损伤模型。     

银杏内酯A对LPS诱导的小鼠急性肺损伤的保护作用

为了研究银杏内酯A对非特异性肺损伤小鼠的保护作用,采用脂多糖（LPS）滴鼻法建立了小鼠急性肺损伤（ALI）模型。于造模前1h给予银杏内酯A（50,100mg/kg）,在LPS滴入后18h检测支气管肺泡灌洗液（BALF）中的细胞因子TNF-α、IL-6、IL-1β水平,观察肺部组织学的病理变化。结果表明：银杏内酯A可以显著抑制肺组织中炎性细胞的浸润,抑制肿瘤坏死因子α（TNF-α）、白细胞介素6（IL-6）和白细胞介素1β（IL-1β）炎性细胞因子的产生。由此得出结论,银杏内酯A对LPS诱导的小鼠ALI具有一定的保护作用。     

脂多糖刺激对仔猪下丘脑-垂体-肾上腺轴Toll样受体4信号通路关键基因表达的影响

本试验旨在研究脂多糖(LPS)刺激对仔猪下丘脑-垂体-肾上腺(HPA)轴Toll样受体4(TLR4)信号通路关键基因表达的影响。选取12头断奶仔猪,分成2个组,每个组6个重复。试验组注射100μg/kg体重的LPS,对照组注射等量的生理盐水。注射LPS或生理盐水4 h后采血,测定血浆中与应激相关激素的含量;采血后屠宰仔猪,取下丘脑、垂体、肾上腺,测定TLR4信号通路关键基因的mRNA表达水平,包括TLR4、髓样分化因子88(My D88)、白细胞介素-1受体相关激酶1(IRAK1)、肿瘤坏死因子受体相关因子6(TRAF6)和核转录因子-κB(NF-κB)mRNA表达水平。结果表明:与对照组相比,1)LPS刺激导致血浆肿瘤坏死因子-α、皮质醇和促肾上腺皮质激素含量显著上升(P<0.05)。2)LPS刺激导致TLR4信号通路关键基因TLR4在下丘脑、垂体、肾上腺中mRNA表达水平显著升高(P<0.05);My D88在垂体、肾上腺中mRNA表达水平显著升高(P<0.05),在下丘脑中mRNA表达水平有升高的趋势(P<0.10);IRAK1在垂体、肾上腺中mRNA表达水平有升高的趋势(P<0.10);TRAF6在下丘脑、垂体、肾上腺中mRNA表达水平显著升高(P<0.05);NF-κB在垂体中mRNA表达水平显著升高(P<0.05)。试验结果表明LPS刺激激活了HPA轴,诱导了HPA轴的TLR4信号通路关键基因的表达。     

外源激活乳过氧化物酶体系对生鲜牛乳保鲜效果的影响

采用外源激活不同组分浓度的乳过氧化物酶体系进行研究,试验分为A,B和C组,各组生鲜牛乳中依次分别加入NaSCN 12,15和20 mg.L-1后,再分别都加入H2O29μL.L-1,旨在对比研究其对生鲜牛乳的保鲜效果.结果表明,外源激活不同组分浓度的LPS对生鲜牛乳都具有保鲜作用,但保鲜效果不同.试验A,B和C组的牛乳保鲜期分别为17,20.5和21 h,与对照组相比,分别延长了4,8和8.5 h,同时还提高了1~2个卫生等级,表明B组和C组比A组保鲜效果好,但由于C组牛乳中的SCN-含量超过了规定,因此以B组的保鲜效果最佳.     

赶黄草总黄酮对小鼠肝损伤的保护作用

为研究赶黄草总黄酮对脂多糖(LPS)诱发的肝损伤的保护作用,将50只昆明种小鼠随机分为空白组、模型组、联苯双酯阳性对照组及赶黄草总黄酮高、低剂量组,每组10只。赶黄草总黄酮高、低剂量组分别按照10 mg/kg、2 mg/kg的剂量灌服;联苯双酯阳性对照组按照5 mg/kg的剂量灌服;空白组和模型组分别灌胃等容积的生理盐水。连续给药14 d,观察小鼠生长状况,末次给药之后2 h,空白组尾静脉注射生理盐水2 m L/kg,其余各组尾静脉注射5 mg/kg LPS,12 h后眼球取血处死小鼠,测定小鼠血清中谷丙转氨酶(ALT)和谷草转氨酶(AST)活性以及肝匀浆中的超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量。同时将肝脏进行HE染色,观察小鼠肝脏组织病理学变化。结果显示,赶黄草总黄酮对小鼠生长有抑制作用。与模型组比较,赶黄草总黄酮高、低剂量组血清中ALT活性分别降低26.53%(P0.01)、16.74%(P0.05),AST活性分别降低12.50%(P0.05)、9.88%(P0.05),SOD活性分别升高26.46%(P0.05)、21.77%(P0.05),MDA含量分别降低48.73%(P0.05)、59.80%(P0.01);小鼠肝脏指数分别降低10.36%(P0.05)、3.80%(P0.05);赶黄草总黄酮各剂量组肝组织病变程度明显减轻。以上结果表明,赶黄草总黄酮对LPS诱导的小鼠肝损伤有保护作用。     

Molecular characterization of Portuguese strains of Yersinia ruckeri isolated from fish culture systems

A total of 23 Portuguese strains of Yersinia ruckeri , the causative agent of enteric redmouth disease (ERM), were comparatively studied by means of lipopolysaccharide (LPS) and outer membrane protein (OMP) analysis, plasmid profiling and ribotyping in order to investigate the heterogeneity among isolates and the usefulness of these methods as epidemiological markers. Only two LPS profiles were observed among the isolates studied, corresponding with the serotypes O1 and O3 of Y. ruckeri . A higher heterogeneity was detected analysing the OMP, seven different patterns being observed. Although some isolates carried different small plasmids, all the serotype O1 isolates showed a plasmid band of 50 MDa and all the serotype O3 strains shared in common a extrachromosomic DNA band of 30 MDa. The analysis of the ribopatterns obtained using three different enzymes, separated the strains into 10 ribotypes, indicating genetic heterogeneity among the isolates. The heterogeneity was greater within serotype O1 isolates, six ribotypes being detected, than within serotype O3 in which only three ribotypes were found. Although OMP analysis and ribotyping can be useful for the differentiation of strains on the basis of farm and/or season of isolation, we consider that ribotyping is the best candidate for epidemiological studies because it is easier to perform and offers a slightly better discriminative power.