猪肠道钠氢交换载体(NHE3)mRNA表达的肠段特异性和发育性变化

旨在探讨猪肠道钠氢交换载体（NHE3）mRNA表达的肠段特异性和发育模式,为NHE在养猪生产中的应用提供理论依据。选取遗传背景相同的1、7、26、30、60、90和150 d蓝塘和长白公猪各5头,测体质量后屠宰,取十二指肠、空肠、回肠和结肠组织样品;以18S rRNA为内标基因,用实时荧光定量PCR法检测NHE3 mRNA在60 d长白猪表达的肠段特异性及其在蓝塘和长白猪肠道表达的发育模式。结果显示：长白猪肠道NHE3 mRNA的表达丰度为结肠、十二指肠、空肠和回肠依次降低,且结肠显著高于空肠和回肠（P〈0.05）。不同猪种NHE3mRNA在十二指肠和空肠的表达模式相似;蓝塘和长白猪NHE3 mRNA的表达丰度分别在7和30 d（十二指肠）、7和26 d（空肠）达最高水平（P〈0.05）。不同猪种结肠NHE3 mRNA的表达模式不同,分别与其在十二指肠和空肠的发育呈现不同的模式;蓝塘猪结肠NHE3 mRNA的表达丰度在26、90和150 d时显著低于长白猪（P〈0.05）。以上结果说明,猪肠道NHE3 mRNA的表达受到发育阶段、品种和肠段的调控,且在十二指肠和空肠间具有品种稳定性。     

鸡不同肠段碱性氨基酸转运载体mRNA表达的差异性研究

为研究肉鸡肠道不同肠段碱性氨基酸转运载体rBAT(系统b0, )、y LAT2(系统y L)、CAT1(系统y )、CAT4(系统y )mRNA表达的差异性,以快大型黄羽肉鸡为动物模型,采集30日龄接近平均体重黄羽肉鸡的十二指肠、空肠、回肠和结直肠样品,采用相对定量RT-PCR方法研究不同肠段rBAT、y LAT2、CAT1、CAT4mRNA表达丰度。结果显示:结直肠rBAT、y LAT2的mRNA表达丰度极显著低于十二指肠、空肠和回肠(P<0.01),其在回肠表达丰度高于空肠、十二指肠,差异不显著(P>0.05)。结直肠CAT1 mRNA表达丰度极显著高于十二指肠、空肠和回肠(P<0.01),回肠极显著高于空肠(P<0.01),高出十二指肠27.9%(P=0.111)。结直肠CAT4 mRNA的表达丰度极显著高于其他各个肠段(P<0.01),十二指肠、空肠、回肠CAT4 mRNA的表达丰度依次降低,但相互之间无显著差异。结果表明,位于肠上皮黏膜细胞顶端的碱性氨基酸转运系统b0, 和基底部位的系统y L转运载体mRNA的表达在肠道中的分布类似,显著区别于系统y 。     

牛源致病性大肠埃希菌K99对小鼠肠绒毛生长和肠三叶因子mRNA表达的影响

通过研究大肠埃希菌对小鼠肠绒毛生长和肠三叶因子mRNA表达的影响,探讨牛源致病性大肠埃希菌感染与肠黏膜上皮细胞再生的相互关系。选取Balb/c小鼠,分成空白对照组、Brdu组(Brdu)和E.coli感染组(Brdu+E.coli),并于不同时间点(6、12、24、30、36、48、60h)采集小鼠十二指肠、空肠和回肠组织。用HE染色观察病理组织学变化,并测量肠绒毛长度和隐窝深度;用免疫组化染色检测肠黏膜上皮细胞中Brdu阳性信号;用PAS染色检测杯状细胞数;用real-time PCR检测肠黏膜组织中ITF mRNA表达水平。结果显示,空白对照组和Brdu组肠组织结构无明显变化。E.coli感染小鼠肠组织6h^36h后,十二指肠、空肠绒毛萎缩或崩解成碎片脱落,隐窝变深;其他时间未见明显变化。E.coli感染小鼠后6h^36h,Brdu阳性信号在上皮细胞中的移动距离极显著高于Brdu组(P<0.01)。E.coli感染小鼠后6h^60h,十二指肠、空肠、回肠中的杯状细胞数均显著低于空白对照组和Brdu组(P<0.01)。E.coli感染小鼠后6h^36h,小肠组织中ITF mRNA表达极显著低于空白对照组和Brdu组(P<0.01)。牛源致病性E.coli感染小鼠后,既可引起小肠黏膜上皮细胞的损伤和抑制ITF mRNA表达,也能够促进小肠绒毛上皮细胞的生长。     

不同磷水平对Na+/PiⅡb转运载体蛋白mRNA表达和磷吸收的影响

本文通过大鼠饲喂试验研究了不同磷水平对磷吸收的影响,旨在进一步揭示无机磷的吸收机理.试验选用120只体重相近的昆明大白鼠,随机分成4个处理,每处理5个重复,每个重复6只大白鼠,分别饲喂含磷(总磷)0.2%、0.4%、0.6%、0.8%的饲粮,试验期14d,测定血钙血磷、骨钙骨磷及不同肠段Na+/PiⅡb载体转运蛋白mRNA表达量和磷的吸收等指标.结果表明,0.2%低磷组回肠、空肠、十二指肠Na+/PiⅡb载体转运蛋白mRNA表达量分别是0.6%磷水平组的3.10(P<0.01)、3.07(P<0.01)、2.17倍(P<0.05);但肾脏中Na+/PiⅡb mRNA表达量比其他3个磷水平组分别低9.19、12.86、23.15倍,差异均极显著(P<0.01);0.2%低磷组中回肠Na+/PiⅡb mRNA表达量分别是空肠、十二指肠和肾脏的1.34(P>0.05)、3.43(P<0.05)和95.53倍(P<0.01);肾脏中Na+/PiⅡb mRNA的表达量最低,分别比空肠、十二指肠低70.92、27.85倍,差异均极显著(P<0.01).0.2%低磷组磷吸收比0.6%和0.8%磷水平组分别提高了22.11%(P<0.05)和19.35%(P<0.05),同时还提高了血清中维生素D3含量(P<0.05).研究表明,低磷提高了小肠中Na+/PiⅡb载体转运蛋白mRNA表达量和磷的吸收,且在低磷条件下,大鼠Na+/PiⅡb载体转运蛋白mRNA表达量以回肠最高,肾脏最低.     

猪肠道碱性氨基酸转运载体(CAT1)mRNA表达的组织特异性和发育性变化

本研究旨在探讨不同品种猪肠道碱性氨基酸转运载体（CAT1）mRNA表达的组织特异性和发育规律。试验选取1、7、26、30、60、90和150日龄长白和蓝塘公猪各5头（同一品种同一日龄且体重接近）,共70头,测体重后屠宰,采集十二指肠、空肠、回肠和结肠组织样品。以18S基因为内标,用实时荧光定量RT-PCR法（SYBR Green Ⅰ试剂盒）检测CAT mRNA在60日龄长白猪十二指肠、空肠、回肠和结肠表达的组织特异性,以及在长白和蓝塘猪不同日龄其十二指肠、空肠、回肠表达的发育性变化。结果显示：60日龄长白猪CAT1 mRNA的表达丰度从十二指肠到回肠呈逐渐升高的趋势,到结肠开始下降,回肠极显著高于其他3个肠段（P〈0．01）,十二指肠最低;十二指肠和空肠CAT mRNA的表达在1～26d（即哺乳期）都呈上升的趋势,随后都开始有所下降;蓝塘猪十二指肠CAT1 mRNA的表达丰度在150d时显著低于其他各个阶段（P〈0．05）,而长白猪90和150d都显著低于其他各阶段（P〈0．05）;空肠CAT1 mRNA的表达在26～150d各阶段都差异不显著,而26d显著高于1和7d（P〈0．05）;1～60d长白和蓝塘猪回肠CAT1 mRNA的表达都呈逐渐上升的趋势,60d后都显著下降（P〈0．05）。两品种猪不同日龄时十二指肠和空肠CAT1 mRNA的表达量都没有显著差异（P〉0．05）;长白猪回肠CAT mRNA表达在26d时显著高于蓝塘猪（P〈0．05）;在90和150d时,长白猪都显著低于蓝塘猪（P〈0．05）,其他各阶段没有显著差异。结果说明,CAT mRNA在不同肠段及不同发育阶段的表达存在明显的差异,这可能与肠腔中氨基酸的浓度和氨基酸的需要水平及相关激素水平有关。     

色氨酸对产肠毒素大肠杆菌感染SD大鼠肠道的防御作用

旨在研究色氨酸对产肠毒素大肠杆菌(ETEC)感染损伤SD大鼠肠道的防御作用。本试验采用2*2双因子试验设计,将40只28日龄雌性SD大鼠,体质量(68.41±0.29)g,随机分为4组:基础日粮组(B);ETEC攻毒组(E,1.0×10^8 ETEC K88);色氨酸缺乏组(I,0.1 mL/d、10 g/L依那普利)。色氨酸缺乏+ETEC攻毒组(E+I,1.0×10^8 ETEC K88+0.1 mL/d、10 g/L依那普利),每组10个重复,每个重复1只。采用H.E染色组织切片观察、酶联免疫吸附测定(ELISA)、三重聚合酶链式反应(PCR)、免疫蛋白印迹、实时荧光定量(RT-PCR)和变性梯度凝胶电泳(DGGE)法分别对SD大鼠肠道细胞因子水平、抗菌肽表达和蛋白水平、粪便中ETEC数量以及盲肠微生物区系变化进行检测。结果表明,依那普利通过抑制ACE2酶阻碍肠道色氨酸吸收,显著降低大鼠空肠和回肠黏膜绒毛高度、淋巴细胞数量和绒毛高度/隐窝深度值(P<0.05);ETEC攻毒显著降低大鼠空肠淋巴细胞数量、绒毛高度/隐窝深度值(P<0.05)和回肠绒毛高度和淋巴细胞数量(P<0.05)。ETEC攻毒使SD大鼠粪便中ETEC数量显著增高(P<0.05)。依那普利抑制剂对SD大鼠粪便中ETEC数量无显著影响(P<0.05);依那普利通过抑制ACE2酶阻碍肠道色氨酸吸收增加空肠和回肠IL-6(P<0.05)和空肠TNF-α质量浓度(P=0.059),降低空肠TGF-β质量浓度(P=0.056);ETEC攻毒使空肠IL-6和回肠IL-6、IL-8和TNF-α质量浓度显著增加(P<0.05),降低空肠TGF-β质量浓度(P=0.059)。依那普利通过抑制ACE2酶阻碍肠道色氨酸吸收显著降低大鼠空肠和回肠Defa-5、BD-2基因mRNA相对表达量(P<0.05);ETEC攻毒使空肠Defa-5、IDO基因和回肠IDO基因mRNA相对表达量显著增加(P<0.05);依那普利通过抑制ACE2酶阻碍肠道色氨酸吸收使空肠、回肠mTOR、BD-2蛋白水平显著降低(P<0.05),使空肠TLR-4蛋白水平显著增加(P<0.05)。色氨酸缺乏、ETEC攻毒降低盲肠微生物多样性,降低拟杆菌门微生物数量,色氨酸不缺乏组盲肠微生物多样性优于缺乏组。结果显示色氨酸通过维持肠道炎性细胞因子浓度稳定、促进肠道黏膜发育和提高肠道抗菌肽基因表达改善肠道微生态环境,对ETEC感染SD大鼠肠道具有防御作用。     

术苦芩总多糖对湿热泄泻仔猪小肠杯状细胞数量以及MUC-2和ITF-3 mRNA转录的影响

为探讨术苦芩总多糖(ZKQPs)对湿热泄泻仔猪小肠修复作用的影响,将60头断奶仔猪分为空白对照组(n=10)造模组(n=50),造模组采用高温高湿环境配合高脂配合饲料等建立湿热泄泻模型,进一步将造模成功后的50头仔猪随机分为模型组、阳性药物组(白头翁散)、ZKQPs高、中、低剂量组(n=10),分别拌料给药,连用7d。采用过碘酸雪夫染色(PAS)结合显微镜观察小肠组织杯状细胞(GC),利用RT-PCR和ELISA分别检测湿热泄泻仔猪小肠黏液中黏蛋白-2(MUC-2)和肠三叶因子(ITF-3)的转录和含量变化。试验结果:1)模型组仔猪十二指肠、空肠、回肠中GC数量均减少,与空白组比较,差异显著(P<0.05);与模型组比较,ZKQPs高剂量组、中剂量组和阳性药物组仔猪十二指肠、空肠、回肠中GC数量均增加,ZKQPs高剂量组、阳性药物组仔猪十二指肠、空肠、回肠和ZKQPs中剂量组仔猪十二指肠、回肠GC的数量差异显著(P<0.05)。2)与空白组比较,模型组仔猪十二指肠、空肠、回肠中MUC-2mRNA的转录量和含量均降低,差异显著(P<0.05或P<0.01)。与模型组比较,ZKQPs各剂量组和阳性药物组仔猪十二指肠、空肠、回肠中MUC-2mRNA的转录量和含量均升高,ZKQPs高剂量组和阳性药物组仔猪十二指肠、空肠、回肠MUC-2mRNA的转录量和含量差异显著(P<0.05或P<0.01)。3)与空白组比较,模型组仔猪十二指肠、空肠、回肠中ITF-3mRNA的转录量和含量均降低,差异极显著(P<0.01)。与模型组比较,ZKQPs高剂量组、中剂量组和阳性药物组仔猪十二指肠、空肠、回肠中ITF-3mRNA的转录量和含量均升高,ZKQPs高剂量组、中剂量组和阳性药物组仔猪空肠、回肠中ITF-3mRNA的转录量和含量差异显著(P<0.05或P<0.01)。ZKQPs可提高湿热泄泻仔猪小肠GC的数量以及MUC-2和ITF-3mRNA的转录,促进湿热泄泻仔猪小肠内GC分泌物MUC-2和ITF-3分泌。     

蛋鸡小肠肽转运载体PepT1表达差异性的评定

本试验旨在研究蛋鸡十二指肠、空肠、回肠小肽转运载体mRNA表达的差异性.选用相同背景的健康成年蛋鸡10只,从十二指肠、空肠、回肠组织提取RNA样品,采用相对定量RT-PCR,对蛋鸡小肠各段肽转运载体mRNA表达的差异性进行评定.结果表明,蛋鸡空肠PepT1 mRNA的表达水平显著高于十二指肠(P＜0.05),与回肠比差异不显著(P＞0.05),十二指肠PepT1 mRNA的表达水平与回肠之间无显著差异(P＞0.05).     

饲粮阴阳离子差水平对围产期小鼠血钙浓度与胃肠道组织维生素D受体mRNA表达水平的影响

本试验旨在通过研究饲粮阴阳离子差(DCAD)水平对围产期小鼠血钙浓度和胃肠道组织维生素D受体(VDR)mRNA表达水平的影响,揭示低DCAD水平防治低血钙症的作用机理。将120只围产期小鼠分为3组,每组40只,分别饲喂DCAD水平为+300(高DCAD水平组,HD组)、+150(对照组,CON组)、-150 mmol/kg DM(低DCAD水平组,LD组)的饲粮。在小鼠产前20 d(-20 d)、产前5 d(-5 d)、产仔当天(0 d)、产后3 d(3 d),每组随机选取10只采血并采集胃、十二指肠、空肠、回肠、盲肠、结肠样品,测定血钙浓度与组织VDR mRNA表达水平。结果表明:在整个试验期和单个采血时间点,LD组较CON组、HD组显著提高小鼠血钙浓度(P0.05)。与CON组、HD组相比,在-20 d,低DCAD水平显著提高了空肠、回肠和结肠的VDR mRNA表达水平(P0.05);在-5 d,低DCAD水平显著提高了空肠、结肠VDR mRNA表达水平;在0 d,低DCAD水平显著提高了十二指肠VDR mRNA表达水平(P0.05);在+3 d,低DCAD水平显著提高了十二指肠、空肠和结肠VDR mRNA表达水平(P0.05)。由此可见,低DCAD水平可提高围产期小鼠胃肠道组织VDR mRNA表达水平,增加血钙浓度。这可能是低DCAD水平有效防治低血钙症的作用机理。     

术苦芩多糖对湿热泄泻仔猪小肠Notch信号通路干预的探究

为探讨复方术苦芩有效成分术苦芩多糖(ZKQPs)对湿热泄泻仔猪小肠Notch信号通路的干预,进一步阐明ZKQPs对湿热泄泻仔猪小肠修复作用机制。将60头断奶仔猪分为空白对照组(n=10)与造模组(n=50),并将造模成功后的50头仔猪随机分为模型组、阳性药物组、ZKQPs高、中、低剂量组,每组10头,拌料给药,连用7 d。每天观察各组仔猪临床症状,统计有效率、治愈率作为评价指标。用RT-PCR法检测湿热泄泻仔猪小肠组织中Notch-1、Hes-1和Hath-1的mRNA表达情况。模型组仔猪十二指肠、空肠、回肠中Notch-1 mRNA表达量升高,ZKQPs各剂量组仔猪十二指肠、空肠、回肠中Notch-1 mRNA表达量降低,其中ZKQPs高剂量组仔猪十二指肠、空肠、回肠中Notch-1 mRNA表达量,与模型组比较,差异显著(P<0.05)。模型组仔猪十二指肠、空肠、回肠中Hes-1 mRNA表达量升高,ZKQPs各剂量组仔猪十二指肠、空肠、回肠中Hes-1 mRNA表达量降低,除ZKQPs低剂量组仔猪十二指肠和空肠外,其余ZKQPs各剂量组仔猪十二指肠、空肠、回肠中Hes-1 mRNA表达量,与模型组比较,差异极显著(P<0.01)。模型组仔猪十二指肠、空肠、回肠中Hath-1 mRNA表达量降低,ZKQPs各剂量组仔猪十二指肠、空肠、回肠中Hath-1 mRNA表达量升高,与模型组比较,差异极显著(P<0.01)。ZKQPs可通过降低仔猪小肠Notch信号通路中Notch-1、Hes-1的mRNA表达量和升高Hath-1 mRNA表达量来发挥修复肠道作用,达到治疗仔猪湿热泄泻。     

Tissue distribution and disposition kinetics of enrofloxacin in healthy and E. coli infected broilers

Concentrations of enrofloxacin equivalent activity were determined by microbiological assay in the plasma of healthy and E. coli-infected broilers following single intravenous and oral administrations at 10 mg/kg. Tissue distribution and residue-depletion following multiple oral doses (10 mg/kg for 3 successive days) were investigated. Pharmacokinetic variables were determined using compartmental and non-compartmental analytical methods. Plasma enrofloxacin concentrations after intravenous dosing to healthy and infected birds were best described by a two-compartments model. Enrofloxacin concentrations in plasma of infected birds were lower than those of healthy ones. The disposition kinetics of intravenously administered drug in healthy and infected birds were somewhat different. The elimination half-life (t1/2 beta) was 4.75 vs. 3.63 h; mean residence time (MRT) was 6.72 vs 4.90 h; apparent volume of the central compartment (Vc) was 1.11 vs 1.57 l/kg; rate constant for transfer from peripheral to central compartment (k21) was 1.15 vs 1.41 h-1 and total body clearance (ClB) was 0.35 vs 0.53 l/h/kg in healthy and infected birds, respectively. After oral administration, the absorption half-life (t1/2abs) in the infected birds was significantly longer than in healthy birds, while elimination half-life (t1/2el) and MRT were significantly shorter. Bioavailability was higher in infected birds (72.50%) as compared to healthy ones (69.78%). Enrofloxacin was detected in the tissues of healthy and infected birds after daily oral dosing of 10 mg/kg for 3 days. It was more concentrated in liver, kidney, and breast muscle. The minimal inhibitory concentration (MIC) of enrofloxacin against E. coli was 0.064 microgram/ml. On the basis of maintaining enrofloxacin plasma concentrations over the MIC, a dose of 10 mg/kg given intravenously every 20.14 hrs or orally every 20.86 hrs should provide tissue concentrations effective against E. coli infection in chickens.     

Tumor necrosis factor-alpha and nitrite/nitrate responses during acute mastitis induced by Escherichia coli infection and endotoxin in dairy cows

Concentrations of tumor necrosis factor-alpha (TNF-alpha) and of NO(x) (sum of nitrite and nitrate as indicators of endogenous nitric oxide production) in milk and blood plasma were measured in three mastitis models in dairy cows in early lactation. Escherichia coli P4:O37 bacteria or endotoxin O111:B4 were administered into both left quarters of 12 and 6 cows, respectively. Six of the E. coli-infected cows were treated with a bactericidal antibiotic (Enrofloxacin; Bayer AG, Leverkusen, Germany) i.v. at 10 hr and subcutaneously (sc) at 30 hr after infection. NO(x) concentrations transiently increased maximally 10- to 11-fold in milk of E. coli-infected quarters with or without antibiotic treatment at 24 hr and after endotoxin administration. NO(x) concentrations did not change in milk of unchallenged quarters and in blood plasma. Increases of NO(x) were proceeded by a transient (96- to 149-fold) rise of milk TNF-alpha concentrations, which in endotoxin-administered quarters was maximal at 6 hr and in infected quarters without or with Enrofloxacin treatment at 10 and 14 hr. In blood plasma TNF-alpha concentrations only moderately increased to peaks in endotoxin-administered cows at 6 hr and in E. coli-infected cows at 14 hr postchallenge. In one severely sick, nontreated E. coli-infected cow milk, TNF-alpha response at 14 hr was excessive and followed by a spectacular rise of NO(x) concentration in milk between 48 and 72 hr. In conclusion, a possible clinical relevance of nitric oxide production associated with a rise of intramammary and systemic TNF-alpha during acute mastitis by E. coli infection and endotoxin in lactating dairy cows is indicated, but could not be inhibited by antibiotic treatment.     

布劳恩脂蛋白对大肠埃希氏菌感染导致的小鼠体内细胞因子分泌及死亡的调节作用

细菌外膜成分布劳恩脂蛋白(Braun lipoprotein,BLP)在调控大肠埃希氏菌感染导致的宿主炎症反应过程中发挥的具体作用尚不清楚。该研究分析了野生型大肠埃希氏菌(BLP表达阳性)、大肠埃希氏菌JE5505(BLP表达阴性)和大肠埃希氏菌JE5505与BLP联合刺激小鼠后,体内促炎性细胞因子(TNF-α和IL-1β)、抗炎因子(IL-10)和趋化因子(RANTES)分泌的情况,以及小鼠的存活率和脏器的损伤水平。结果表明,大肠埃希氏菌JE5505组感染小鼠后导致死亡的速度比野生型大肠埃希氏菌组和大肠埃希氏菌JE5505与BLP联合刺激组更迅速;JE5505与BLP联合刺激组在感染20 h后小鼠不再出现死亡。在大肠埃希氏菌JE5505感染的小鼠血清、肝脏和肺脏中,促炎性细胞因子和趋化因子的分泌水平显著高于、抗炎细胞因子显著低于野生型大肠埃希氏菌组和大肠埃希氏菌JE5505与BLP联合刺激组的小鼠(P<0.01)。此外,BLP的存在可下调大肠埃希氏菌感染导致小鼠脏器中组织损伤标志物HMGB1和HABP2的蛋白表达(P<0.05)。说明细菌外膜成分BLP耐受可能通过调节炎症介质的产生,进而对细菌感染导致宿主脏器损伤和炎症反应发挥调控和保护作用,从而避免小鼠在被大肠埃希氏菌感染后出现快速死亡的现象。     

Production of muraminidase-released protein (MRP), extracellular factor (EF) and suilysin by field isolates of Streptococcus suis capsular types 2, 1/2, 9, 7 and 3 isolated from swine in France

A total of 323 isolates of Streptococcus suis recovered from diseased or healthy pigs in France were serotyped. The presence of virulence-related proteins, Muraminidase-Released Protein (MRP), Extracellular Factor (EF) and Suilysin was also studied in 122 isolates of capsular types 2, 1/2, 9, 7 and 3 to evaluate their implication in virulence of S. suis. Capsular types 2, 1/2, 9, 7 and 3 were the most frequently detected (93%), with 69% for the capsular type 2 alone. Capsular types 2, 1/2, 9, 7, 3, 1, 4, 8, 18, 10 and 12 were isolated from diseased pigs, whereas types 2, 7, 9, 1/2, and 3 originated from the nasal cavities or tonsils of healthy animals. Most of the S. suis type 2 isolates recovered from diseased pigs carried MRP+ EF- Suilysin- (46%) or MRP+ EF+ Suilysin+ (28%) phenotypes. The MRP+ EF- Suilysin- phenotype was also detected in 67% of S. suis type 2 strains isolated from healthy pigs. The production of the virulence-related proteins was less frequently found in S. suis types 1/2, 9, 7 and 3 recovered either from diseased or healthy pigs. In this study, all the capsular type 1/2 strains were MRP+ EF- Suilysin- and all the S. suis type 7 harboured an MRP- EF- Suilysin- phenotype. The MRP- EF- Suilysin- phenotype was found in S. suis types 2, 3, 7 and 9 isolated from septicaemia, meningitis, pneumonia, and pleurisy. These results suggest that the presence of these proteins should not be used as a single condition for classifying the virulence of a field isolate in France.     

The presence of muramidase released protein and extracellular factor protein in various serotypes of Streptococcus suis isolated from diseased and healthy pigs in Spain

A total of 142 strains from different serotypes of Streptococcus suis isolated in Spain from diseased pigs (88 strains) and healthy carrier pigs (54 strains) were studied for the presence of a muramidase released protein (MRP) and an extracellular factor (EF). The following five phenotypes: MRP+EF+, MRP+EF-, MRP-EF+, MRP+EF* and MRP*EF- were detected. A high percentage of S. suis serotype 2 strains isolated from diseased pigs (84 per cent) belonged to phenotype MRP+EF+, but this phenotype has also been noticed in other serotypes (serotypes 1, 1/2 and 14). Both proteins were detected in S. suis serotype 2 strains (26%) isolated from healthy carrier pigs and one of both proteins in serotypes 1 and 14 (phenotype MRP+EF*). The isolation of S. suis strains from healthy pigs which have shown both proteins may support the epidemiological significance of these carriers in the maintenance, transmission and distribution of virulent strains within and between swine farms.     

Epidemiological relationship of human and swine Streptococcus suis isolates

Two cases of meningitis due to Streptococcus suis in humans are reported here. A butcher and an abattoir worker were referred to a health centre in Castellón (Spain) with fever and symptoms of meningitis. After adequate treatment, a slight hipoacusia persisted as sequelae in both cases. Colonies of S. suis group R, serotype 2 and phenotype MRP+EF+ were isolated from cerebroespinal fluid. Epidemiological studies showed that both workers had in common the handling of pork meat of slaughtered healthy pigs from three closed farms. A study of the tonsils from apparently healthy, slaughtered pigs was carried out. A total of 234 tonsillar samples were obtained and 81 strains of S. suis were isolated from them. Serotype 2 appeared to be the most frequent (50.6%), and the analysis for phenotype showed a high percentage of tonsillar strains with the phenotype MRP+EF+ (35.9%). The humans and 28 tonsillar swine strains showed a similar profile (S. suis group R, serotype 2 and phenotype MRP+EF+). A total of 26 of the swine isolates were analysed by ribotyping using EcoRI. The human strains showed the same six-band hybridization pattern that shared five bands with the pattern most frequently shown by most of the tonsillar N. suis group R, serotype 2 and phenotype MRP+EF+ strains, differing only in the lightest, faintest band which was slightly less anodical in human (> or = 1.8 kb) than in swine (approximately 1.8 kb). From these results, both groups of strains, humans and porcine, showed differences; how can these differences in the pattern of ribotyping be explained if they should have the same origin? Is it possible that they have undergone an adaptation to the new host or perhaps the modification is due to other unknown causes? Further studies in this area are required in order to answer these questions.     

Production of virulence-related proteins by Canadian strains of Streptococcus suis capsular type 2.

The production of muramidase-released protein (MRP), extracellular protein factor (EF) and hemolysin (suilysin) by 101 Canadian field strains of Streptococcus suis capsular type 2 is described. Most strains (72%) isolated from diseased pigs were MRP-EF- and only 1 strain was MRP+EF+. This strain was also the only 1 to produce the hemolysin. Thirteen strains (15%) were MRP+ EF- and only 3 strains were MRP* EF-. All the strains isolated from clinically healthy pigs as well as a bovine and 2 human isolates had a MRP-EF- phenotype. In addition, 7 strains (8%) had a MRPS phenotype, which had so far been described for S. suis capsular type 1. In conclusion, most Canadian field isolates of S. suis capsular type 2 tested in this study do not produce the virulence-related proteins described so far for this bacterial pathogen.     

Expression and localization of BCRP,MRP1 and MRP2 in intestines,liver and kidney in horse

Tydén, E., Bj?rnstr?m, H., Tjälve, H., Larsson, P. Expression and localization of BCRP, MRP1 and MRP2 in intestines, liver and kidney in horse. J. vet. Pharmacol. Therap. doi: 10.1111/j.1365‐2885.2009.01140.x. The gene and protein expression and the cellular localization of the ABC transport proteins breast cancer resistance protein (BCRP), multidrug resistance‐associated protein 1 (MRP1) and multidrug resistance‐associated protein 2 (MRP2) have been examined in the intestines, liver and kidney in horse. High gene and protein expression of BCRP and MRP2 were found in the small intestines, with cellular localization in the apical membranes of the enterocytes. In the liver, MRP2 was present in the bile canalicular membranes of the hepatocytes, whereas BCRP was localized in the cytoplasm of hepatocytes in the peripheral parts of the liver lobuli. In the kidney both BCRP and MRP2 were predominantly present in the distal tubuli and in the loops of Henle. In most tissues, the gene and protein expression of MRP1 were much lower than for BCRP and MRP2. Immunostaining of MRP1 was detectable only in the intestines and with localization in the cytoplasm of enterocytes in the caecum and colon and in the cells of serous acini of Brunner’s glands in the duodenum and the upper jejunum. The latter cells were also stained for BCRP, but not for MRP2. Many drugs used in horse are substrates for one or more of the ABC transport proteins. These transporters may therefore have important functions for oral bioavailability, distribution and excretion of substrate compounds in horse.     

猪链球菌2型人源株MRP的表达及其单克隆抗体的制备与应用

将猪链球菌2型(SS2)人源株Habb mrp基因进行截短修饰后,克隆于pGEX4T-2载体中,转化大肠杆菌诱导表达约61 000的融合蛋白MRP-GST,该蛋白经凝血酶作用去除重组蛋白中的GST标签,得到约35 000纯化的MRP.Western blotting证实MRP可被SS2阳性血清特异性识别.以纯化的MRP抗原免疫BALB/c小鼠,取免疫鼠脾细胞与骨髓瘤细胞SP2/0融合,间接ELISA进行筛选获得了6株能稳定分泌抗MRP特异性单抗的细胞株.特异性试验表明该6株单抗与SS2的另外2种蛋白、大肠杆菌均不发生交叉反应.以2138单抗腹水和SS2多克隆抗血清建立夹心ELISA对71株标准菌株和122株猪链球菌野毒株进行MRP的表征鉴定,标准株检测结果与背景符合率为为97.2%(69/71),其中34株标准血清型菌株检测的符合率为100%.表明该方法可用于猪链球菌的快速诊断和流行病学调查.     

Cold resistance and environmental temperature preference in diarrheic piglets

Piglets aged 12 to 72 h in which diarrhea had been induced by enteric Escherichia coli infection or sucrose gavage were studied with respect to cold resistance and thermal-circulation index in a 90-min test in a 6 C environment (Exp. 1) and free-choice environmental-temperature preference during a 60-min test in a 24 to 44 C thermocline (Exp. 2). In Exp. 1, diarrhea lowered the piglet's ability to maintain body temperature during the cold test. Also, diarrheic piglets tended to have lower thermal circulation index values at the end of the cold test, indicative of a greater vasoconstrictive response to the cold environment. In Exp. 2, mean preferred environmental temperatures were 35.7, 34.9 and 34.5 C, respectively, for piglets in sham-control, E. coli-infected and sucrose-gavaged groups. For reason(s) still unknown, diarrheic piglets did not choose to locate themselves in a warmer niche than did normal piglets; in fact, they did the opposite. Results of the two experiments indicate that diarrheic neonatal piglets need even more attention and care in terms of the thermal environment than do healthy ones.