复合膳食纤维对大鼠体内脂质过氧化作用的影响

制备复合膳食纤维 (dietaryfiber,DF) ,并分别探讨复合、混合及三种单一的DF对高脂血症大鼠体内脂质过氧化作用的影响。选健康、断乳Wistar大鼠 6 4只 ,按体重随机分为 8组 ,用高脂饲料诱发高脂血症的同时 ,分别添加 10 %的DF :纤维素 (B组 )、果胶 (C组 )、海藻酸钠 (D组 )、纤维素 -果胶复合物 (E组 )、纤维素 -海藻酸钠复合物 (F组 )、纤维素 -果胶混合物 (G组 )、纤维素 -海藻酸钠混合物 (H组 ) ,以单纯的高脂饲料组为对照组 (A组 ) ,观察各种DF对大鼠的生长发育及脂质过氧化作用的影响。结果显示 :1、添加 10 %的各种DF不影响大鼠的生长发育。 2、各种DF皆可显著升高血清超氧化物歧化酶 (SOD) (P <0 0 1)、谷胱甘肽过氧化物酶 (GSH Px)活性 (P <0 0 1) ,降低丙二醛 (MDA)水平 (P <0 0 5 ,B、D组除外 ) ,提高红细胞膜的流动性 (P <0 0 5 ) ,以复合物、混合物效果为明显。 3、各种DF可不同程度地增加粪重和粪脂排出量 (P <0 0 5 ,D组除外 ) ,以复合物、混合物为明显。提示各种DF皆可不同程度地降低大鼠体内脂质过氧化作用 ,提高红细胞膜的流动性 ,其中可溶性DF效果优于不可溶性DF ,而复合、混合DF的效果又优于单一的DF ,且以复合物效果为佳     

Kynurenine aminotransferase activity in human liver: identity with human hepatic C-S lyase activity and a physiological role for this enzyme

The C-S lyase enzymes are responsible for the generation of mutagenic and cytotoxic metabolites via aberrant drug-metabolising pathways in mammalian tissues. We have examined human hepatic cytosolic, mitochondrial and microsomal fractions for evidence of C-S lyase activity. The cytosolic enzyme was purified using fast protein liquid chromatography over FFQ Sepharose, Mono P and Superose 12. An homogeneous protein (monitored by SDS-PAGE) was obtained following purification, and an 11-fold increase in C-S lyase specific activity was observed. The molecular weight of the enzyme was found to be 37 kDa in denaturing conditions, 82.3 kDa in non-denaturing conditions, and the C-S lyase activity was shown to co-purify with kynurenine aminotransferase activity when the transaminase activity of the enzyme was examined with kynurenine as the substrate.     

组织工程化口腔粘膜的构建技术初步研究

目的　探索组织工程化口腔粘膜的构建方法。方法　用 Dispase中性蛋白酶分离提取未长毛的 SD乳鼠硬腭口腔粘膜细胞 ,用角化细胞培养液对口腔粘膜细胞进行培养 ,以自制藻酸钠薄膜作为支架材料构建组织工程化的口腔粘膜。结果　 Dispase中性蛋白酶可较好地分离提纯口腔粘膜细胞 ,用 Dispase消化酶分离获取上皮后 ,再用胰蛋白酶消化上皮为单细胞的最佳时间为 10 m in,过低的细胞密度不易形成克隆 ,鼠口腔粘膜细胞培养的最适密度为 1.5× 10 5/ cm2 。角化细胞培养液能对鼠口腔粘膜细胞进行培养 ,且没有成纤维细胞污染 ;口腔粘膜细胞在藻酸钠薄膜上生长良好。结论　利用角化细胞培养液作为培养基 ,藻酸钠薄膜作为支架材料可成功构建组织工程化口腔粘膜     

5-FU纳米微粒的制备及其释药特性研究

目的 制备一种新型的载氟尿嘧啶(5-FU)纳米微粒并对其体内释药特性进行研究.方法 运用聚合物交联法制备出壳聚糖载氟尿嘧啶纳米粒,通过扫描电镜、激光粒度分析仪对其表征进行检测,紫外分光光度法测定载药量,高效液相色谱法检测体内的释药特性.结果 壳聚糖载氟尿嘧啶纳米粒呈圆形或椭圆形,分散性良好,粒径在120～150nm;载药量为31.000%±0.001%;壳聚糖-5-FU纳米粒注射入兔体内后,初期突释相约在1.5h,峰浓度为5 069.6μg/L,随即进入缓释相,浓度维持在76μg/L,时间长达48h.结论 壳聚糖纳米药物载体可改变5-FU在体内的药代动力学行为,延长其循环时间,具有良好的缓释作用.     

海藻酸钙微胶珠的载药性能优化

利用高压静电法制备了海藻酸钙微胶珠，以牛血红蛋白作为模型药物，考察了牛血红蛋白（Hb）的稳定性、制备条件对微胶珠载药的影响。结果表明：Hb在10℃下能稳定存在，1．8％（w／v）Na-Alg与4．5％（w／v）CaCl2制备的微胶珠载药量较大，真空干燥的微胶殊彼此粘连破坏严重，冷冻干燥则表面出现明显的内陷，乙醇梯度洗脱-真空干燥球形度较好。水凝胶态的微胶珠载药后球形度完好，是理想的载药方式，24h时载药量达28．4％，为干燥后的2～3倍。     

Studies on homologous recombination in the green alga Chlamydomonas reinhardtii

The introduction of exogenous DNA into the nuclear genome of Chlamydomonas reinhardtii occurs predominantly via non-homologous (illegitimate) recombination and results in integration at apparently-random loci. Using truncated and modified versions of the C. reinhardtii ARG7 gene in a series of transformation experiments, we demonstrate that homologous recombination between introduced DNA molecules occurs readily in C. reinhardtii, requires a region of homology of no more than 230 bp, and gives rise to intact copies of ARG7 in the nuclear genome. Evidence is presented for homologous recombination between introduced ARG7 DNA and the resident copy of the gene, and for the de-novo synthesis of the ARG7 sequence during transformation.     

Graft copolymer emulsions of sodium alginate with hydroxyallsyl methacrylates for microencapsulation

A hybrid material with interesting capsule forming properties has been prepared by γ-initiated polymerization of hydroxyethyl methacrylate (HEMA) or other acrylic monomers in the presence of aqueous sodium alginate. For example, an aqueous solution of HEMA (1 wt%) and sodium alginate (1 wt%) was irradiated in a γ-source at a dose of 0.15 MR, to produce a stable emulsion which coalesced in the form of a homogeneous precipitate when added to 0.1 M CaCI₂. Polymerization of HEMA was presumed to be initiated by free radicals generated in the alginate by γ-irradiation. The emulsion consisted largely of polyHEMA homopolymer stabilized by an alginate-polyacrylate graft (or block) copolymer of highly branched and ill-defined character, which acts as surfactant to prevent coagulation of the emulsion. Erythrocytes were encapsulated in such an emulsion by extrusion of cell/copolymer emulsion mixture into HEPES buffered CaCI₂ (10 mM Ca). Cells appeared intact and functional after encapsulation. By SEM it appeared that the capsule wall consisted of microspheres of polyHEMA on the inner and outer surfaces held together by the alginate. Furthermore the capsule did not contain the internal meshwork, characteristic of calcium alginate homopolymer gels. Although much remains to be learned about these materials, the combination of the easy gelling characteristics of the alginate with the range of desirable properties (e.g. biocompatibility) afforded by the acrylic monomers may have a significant impact on the development of cell microencapsulation technology.