双歧醋对大鼠预防性减肥的实验研究

目的探讨双歧醋预防大鼠肥胖的作用及相关机制研究。方法 48只SD大鼠被随机分成双歧醋低剂量组[1.8 mL/(kg.BW)]、中剂量组[3.4 mL/(kg.BW)]、高剂量组[6.8 mL/(kg.BW)]和市售醋组[3.4mL/(kg.BW)]、肥胖模型组以及基础对照组,进行预防性减肥实验,观察双歧醋在大鼠肥胖过程中对大鼠的影响,测定指标包括大鼠体重、体脂、Lee’s指数、脂肪细胞直径、血瘦素、血胰岛素。结果实验结果显示,双歧醋各组所有测定指标值都较肥胖组有明显好转,特别是血瘦素和血胰岛素水平,双歧醋的高、中剂量组与市售醋组差异有统计学意义。结论双歧醋能有效预防血瘦素和血胰岛素的升高,预防体脂、Lee’s指数和体重的增加也有一定作用。     

双歧杆菌活菌胶囊预防CPT-11引起的化疗相关性腹泻的疗效观察

目的观察双歧杆菌活菌胶囊预防伊立替康(CPT-11)引起的化疗相关性腹泻的疗效。方法 36例患者随机分成2组,观察组:化疗+双歧杆菌活菌胶囊,对照组:单纯化疗。观察患者治疗前后的KPS评分和腹泻的发生率及分级。结果观察组化疗前后KPS评分无明显变化,对照组化疗后KPS评分明显下降,差异有统计学意义,观察组Ⅰ～Ⅱ级腹泻发生率为33.3%,对照组为50%,2组差异有统计学意义(P<0.01)。观察组Ⅲ～Ⅳ级腹泻发生率为5.5%,对照组为27.8%,2组差异有统计学意义(P<0.01)。结论应用双歧杆菌活菌胶囊预防化疗相关性腹泻有良好的效果。     

急进高原与平原大鼠肠道双歧杆菌的分子生物学实验对比研究

目的探讨应用荧光定量PCR法对急进高原大鼠肠道双歧杆菌数量变化的分子生物学实验研究。方法 Wistar大鼠60只,随机分为2组:平原对照组和3 848米的高原缺氧组各30只。急进海拔3 848米造成大鼠急性缺氧模型并分别于24、6、d取材,每次随机各取10只,观察肠道菌群中双歧杆菌的变化。结果高原缺氧组双歧杆菌数量明显少于平原对照组(P<0.05)。结论急进高原缺氧复杂环境下,可使肠道有益菌———双歧杆菌的数量减少,可能影响肠道微生态平衡。     

富硒转白细胞介素2基因双歧杆菌对小鼠移植瘤H22的治疗作用

目的评价富硒和转白细胞介素2（IL2）基因双歧杆菌对小鼠移植瘤H22的抑制效果。方法通过电转导将含IL2质粒导入到长双歧杆菌（Bifidobacterium longum,B.longum）中,将转IL2基因双歧杆菌接种到添加了亚硒酸钠（Na2SeO3）的培养基中,利用微生物的富集及转化作用,形成富硒的含IL2基因质粒的双歧杆菌（Se-B.longum-IL2）。结果利用双歧杆菌的肿瘤厌氧区靶向性,通过荷肝癌H22的小鼠尾静脉注射Se-B.longum-IL2,取得了良好的抑瘤效果与荷肝癌小鼠生存延长效果。结论转IL2基因双歧杆菌和富硒联合后对小鼠肝癌有明显的基因治疗前景。     

Carbohydrate metabolism in Bifidobacteria

Members of the genus Bifidobacterium can be found as components of the gastrointestinal microbiota, and are believed to play an important role in maintaining and promoting human health by eliciting a number of beneficial properties. Bifidobacteria can utilize a diverse range of dietary carbohydrates that escape degradation in the upper parts of the intestine, many of which are plant-derived oligo- and polysaccharides. The gene content of a bifidobacterial genome reflects this apparent metabolic adaptation to a complex carbohydrate-rich gastrointestinal tract environment as it encodes a large number of predicted carbohydrate-modifying enzymes. Different bifidobacterial strains may possess different carbohydrate utilizing abilities, as established by a number of studies reviewed here. Carbohydrate-degrading activities described for bifidobacteria and their relevance to the deliberate enhancement of number and/or activity of bifidobacteria in the gut are also discussed in this review.     

长双歧杆菌DD98冻干保护剂优化及菌粉保存稳定性研究

以长双歧杆菌DD98为研究对象,通过对冻干保护剂配方的优化,冻干菌粉的存活率提高到90%以上。通过进一步稳定性研究,采用保护剂优化配方制备的冻干菌粉在4℃保存24个月后,活菌数仍在1.0×10^10 CFU/g以上,在25℃条件下可以保存12个月,双歧杆菌的存活率在1.0×10^6CFU/g以上,符合FAO/WHO建议食品益生菌活菌数应在1.0×10^6 CFU/g^1.0×10^7CFU/g的标准。     

Cloned Cytosine Deaminase Gene Expression of Bifidobacterium longum and Application to Enzyme/Pro-drug Therapy of Hypoxic Solid Tumors

Bifidobacterium longum is a nonpathogenic anaerobic bacterium among normal bacterial flora. Recently, it was reported that B. longum accumulated in hypoxic solid tumors. The gene of interest was expressed in transfected B. longum by the shuttle vector pBLES100 in solid tumors. In this report, we constructed pBLES100-S-eCD, which included the cytosine deaminase gene. We confirmed by western blotting that transfected B. longum produced cytosine deaminase. In addition, transfected B. longum produced cytosine deaminase that converted 5-fluorocytosine into 5-fluorouracil. B. longum could be useful for enzyme/pro-drug therapy of hypoxic solid tumors.     

Motif-Guided Identification of a Glycoside Hydrolase Family 1 α-L-Arabinofuranosidase in Bifidobacterium adolescentis

Members of glycoside hydrolase family 1 (GH1) cleave glycosidic linkages with a variety of physiological roles. Here we report a unique GH1 member encoded in the genome of Bifidobacterium adolescentis ATCC 15703. This enzyme, BAD0156, was identified from over 2,000 GH1 sequences accumulated in a database by a genome mining approach based on a motif sequence. A recombinant BAD0156 protein was characterized to confirm that this enzyme alone specifically hydrolyzes p-nitrophenyl-α-L-arabinofuranoside among the 24 p-nitrophenyl-glycosides examined. Among natural glycosides, α-1,5-linked arabino-oligosaccharides served as substrates, but arabinan, debranched arabinan, arabinoxylan, and arabinogalactan did not. A time course analysis of arabino-oligosaccharide hydrolysis indicated that BAD0156 is an exo-acting enzyme. These results suggest that BAD0156 is an α-L-arabinofuranosidase. This is the first report of a GH1 enzyme that acts specifically on arabinosides, providing information on GH1 substrate specificity.     

Separation of the Two Constituent Polypeptide Chains of Ricin D

Two constituent polypeptide chains were isolated from performic acid-oxidized ricin D by DEAE-cellulose column chromatography in phosphate buffer, pH 7.0, containing 8m urea or from reduced-carboxymethylated ricin D by gel filtration on Sephadex G-75 followed by DEAE- cellulose column chromatography in Tris-HCl buffer, pH 8.5. Amino acid analyses of the isolated two chains revealed that they were distinct molecules possessing similar molecular weights of near 30,000 and linked by one disulfide bond in ricin D.     

双歧杆菌质粒聚合酶基因表达系统的构建及其鉴定

目的构建可以在双歧杆菌表达外源性基因的系统。方法PCR扩增双歧杆菌质粒聚合酶基因（BPP）并连接至质粒pBS—T以形成重组质粒pBS—BPP。PCR扩增双歧杆菌内源性阿拉伯糖苷酶的启动子及分泌性信号肽DNA序列（ara）并连接至质粒pBAD—A以形成重组质粒pBAD—ara,然后将增强绿色荧光蛋白（eGFP）基因连接至质粒pBAD—ara以形成重组质粒pBAD—ara—GFP。采用基因重组技术重组含有ara、BPP、eGFP基因序列并可将外源性基因分泌表达于菌体外及锚定表达于细胞壁的质粒pBS—BPP—ara—GFP,激光共聚焦显微镜下观察含有pBS—BPP—ara—GFP质粒及对照质粒的E．coli,验证eGFP定位表达情况。结果所构建的表达系统可以在E．coli中表达eGFP基因。结论通过基因重组方法成功构建了双歧杆菌表达系统,其可将外源基因分泌表达于菌体外。