Effects of pCai and pHi on cell-to-cell coupling

Summary Internal longitudinal resistance (r_i), a determinant of cardiac conduction, is affected by changes in intracellular calcium and protons. However, the role and mechanism by which H⁺ and Ca²⁺ may modulate r_i is uncertain. Cable analysis was performed in cardiac Purkinje fibers to measure r_i during various interventions. In some experiments, intracellular pH (pH_i) was recorded simultaneously to study the pH_i-r_i relation. Both intracellular Ca²⁺ and H⁺ independently modified r_i. However, internal resistance of cardiac fibers was insensitive to pH_i changes compared to other tissues. A latent period preceded the pH_i-related changes in r_i and the amount of change depended upon methodology. The results suggest that direct action of protons on r_i may be subordinate to other regulatory processes. Ionic regulation of internal longitudinal resistance may occur by more than one mechanism: i) direct cationic binding to sites on junctional membrane proteins; and ii) H⁺- or Ca²⁺-dependent phosphorylation of junctional proteins.     

骨桥蛋白在免疫中的作用

骨桥蛋白（OPN）是一种多功能的磷酸化糖蛋白,其涉及多种病理生理学过程.近来研究发现骨桥蛋白通过不同的翻译起始位点产生两种形式的蛋白,即分泌型骨桥蛋白（ sOPN,secreted OPN）和胞内型骨桥蛋白（iOPN,intracellular OPN）.本文主要介绍了sOPN及iOPN在免疫应答中的作用.     

Preparation and cellular uptake of PLGA particles loaded with lamivudine

Poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles loaded with lamivudine and coated with bovine serum albumin (BSA) were prepared via a double emulsion method. The influences of experiments parameters such as volume of inner aqueous phase, concentration of organic phase and ultrasonication time on the particle size and drug entrapment efficiency were investigated, obtaining PLGA particles with a diameter of ~260 nm and drug entrapment efficiency of ~35%. The particles were observed by scanning electron microscopy and transmittance electron microscopy, showing a core-shell structure. BCA assay found that 58 mg BSA was present on/in 1 g LPB particles. The loaded lamivudine showed a burst release at beginning and sustained release until 24 h in physiological conditions. Low pH could accelerate the release of lamivudine from PLGA particles, making the PLGA particles potential intelligent intracellular drug carriers. The PLGA particles were readily internalized into the human liver cells within a short time and increased gradually with the prolongation of incubation time regardless of the loading of lamivudine. The particles either resided within lysosomes or transferred to cytoplasm, but could not enter into the cell nucleus. The cell viability was not significantly influenced in the presence of the particles regardless of lamivudine encapsulation, suggesting that this kind of particles may be a good candidate for the intracellular anti-hepatitis B drug delivery.     

不同木质底物诱导下桦剥管菌细胞内差异蛋白质分析

【目的】研究桦剥管菌在不同木质底物诱导下细胞内蛋白的差异表达情况,探讨桦剥管菌降解木材机理。【方法】以白桦、云杉木屑为诱导底物,利用蛋白质组双向电泳技术(2-DE)结合质谱技术(MALDI-TOF/TOF MS),检测桦剥管菌在不同树种木屑诱导下与对照组(未加木屑)相比菌体胞内蛋白质变化情况,对差异蛋白进行生物信息学分析。【结果】在白桦和云杉木屑诱导下,桦剥管菌细胞内蛋白表达发生了明显变化,处理组(添加木屑)共检测到32个细胞内差异表达蛋白点,经质谱检测及数据库检索,成功鉴定17个差异蛋白点,这些蛋白具有转移酶、水解酶、蛋白结合、细胞信号转导等分子功能,涉及分解代谢、有机物质代谢、氮化合物代谢、初级代谢、细胞生物合成和刺激响应过程。【结论】桦剥管菌降解木材是多种蛋白质共同作用的结果,通过调节多种代谢过程中的相关蛋白表达来发挥作用。     

桑叶多糖提取工艺优化研究

设计了三因素三水平正交试验,对桑叶多糖的提取工艺进行了优化研究,确定出桑叶多糖提取的最佳工艺条件为:料液比1∶9,提取时间90min,提取温度90℃,通过实验验证该工艺条件提取桑叶多糖,多糖得率为8.08%,与三因素三水平正交试验所有实验组对照,大于正交试验中9个组合提取率,这些条件的确定为桑叶的大规模开发和应用奠定了基础。     

茅苍术多糖对Ⅱ型糖尿病大鼠的治疗作用及机制研究

目的探讨茅苍术多糖对Ⅱ型糖尿病大鼠的治疗作用及机制.方法给予Ⅱ型糖尿病模型大鼠不同剂量的茅苍术多糖,通过对模型大鼠体质量改变情况、空腹血糖含量、胰岛素水平及调节血脂代谢紊乱能力的观察,评价其治疗作用;通过对各组大鼠肝脏组织中MDA含量及CAT,SOD酶活性的测定,评价其抗氧化能力.结果茅苍术多糖可以改善糖尿病大鼠体质量下降情况,能够降低空腹血糖含量,提升胰岛素水平;茅苍术多糖也可以降低MDA含量,增加CAT和SOD活性.结论茅苍术多糖具有抗糖尿病作用,其作用机制可能与其抗氧化作用有关.     

榆耳液体发酵菌丝体多糖提取方法的比较研究

以榆耳液体发酵菌丝体为原料,比较研究水提法、酶法和超声波法提取榆耳菌丝体多糖的提取率,结果表明,水提法提取率最低,为3.47%;其次是超声波法,提取率为3.92%;酶法提取率最高,为4.70%.酶法提取效果优于其他两种方法,可显著提高榆耳菌丝体多糖的提取率.     

灵芝多糖的研究进展

灵芝多糖是灵芝的主要有效成分之一。主要就近年来灵芝多糖的提取、分离纯化、含量测定、结构分析、硒化修饰和抗氧化、免疫调节、降血糖、抗肿瘤活性等方面的研究进行了综述。     

一类具有时滞及非线性感染率的病毒感染模型的稳定性及分支分析

将时滞及饱和发生率引入到一类具有初级细胞毒性T淋巴细胞(CTLp)和效应细胞毒性T淋巴细胞(CTLe)免疫反应的病毒感染模型,证明了改进后模型无病毒感染平衡点及无免疫平衡点的全局渐近稳定性.同时,给出了免役应答平衡点(正平衡点)产生Hopf分支的充分条件.最后,数值模拟验证了理论结果.     

柱前衍生化高效液相色谱法测定当归酸性多糖单糖组成的新方法

首次建立柱前衍生化高效液相色谱法分析当归酸性多糖中糖醛酸、氨基糖和中性糖的方法。D-甘露糖、D-葡萄糖胺、L-鼠李糖、D-半乳糖胺、D-葡萄糖醛酸、D-半乳糖醛酸、D-葡萄糖、D-半乳糖、L-阿拉伯糖和D-岩藻糖等10种单糖经柱前衍生化法处理后作为标准品。色谱条件:Hypersil BDS C18色谱柱(4.6 mm i.d.×250 mm,5μm),流动相由乙酸铵水溶液(100mmol/L,p H=5.0)、乙腈和四氢呋喃以81∶17∶2的体积比组成,流动相流速1.0 m L/min,检测波长250 nm,柱温25℃。实验结果表明,当归酸性总多糖是由D-甘露糖、D-葡萄糖胺、L-鼠李糖、D-半乳糖胺、D-葡萄糖醛酸、D-半乳糖醛酸和D-葡萄糖以1.5∶14.1∶1.7∶1.6∶2.0∶2.3∶1.0的摩尔比例组成。