利用纤维二糖差向异构酶制备乳果糖的研究进展

乳果糖是由D-半乳糖和D-果糖两个基团通过β-1,4糖苷键连接而成的还原型二糖;乳果糖口服液具有治疗慢性便秘和肝性脑病的功效,在100多个国家作为常见非处方药(OTC)使用,需求量十分巨大;乳果糖还可以作为益生元改善人体肠道菌群关系。乳果糖的生产依赖化学法,其催化剂对人体有害,下游分离难度大。近年来,纤维二糖差向异构酶被发现能够高效催化乳糖制备乳果糖,该技术绿色环保、步骤简单,具有很强的产业化前景。本文结合自身研究经历对纤维二糖差向异构酶的研发情况进行总结,并综述了乳果糖酶法制备技术的现状。     

高剪切乳化技术辅助提取荷叶水不溶性膳食纤维工艺优化及其物性分析

为扩大荷叶在食品加工中的开发应用性,研究采用高剪切乳化技术辅助提取荷叶水不溶性膳食纤维(insoluble dietary fiber,IDF),优化提取工艺;测定其基本物性,并与常规粉碎、球磨式粉碎处理进行对比。结果表明,在剪切转速8000 rpm剪切时间4 min,酸液浓度0.25 mol/L,酸解温度45℃条件下荷叶IDF得率最高,为83.84%。此荷叶IDF水溶性13.81%,持水性5.65 g/g,持油性1.97 g/g,膨胀性1.93 mL/g。与球磨式粉碎相比,处理时间短,荷叶纤维呈束状、层次分明,荷叶纤维内质未被完全破坏;产品水溶性较低,持水性和膨胀性较高。高剪切乳化技术在食品纤维组分的加工中具有较好的应用潜力。     

Preparation and Evaluation of Electrospun Zein/HA Fibers Based on Two Methods of Adding HA Nanoparticles

Zein/HA fibrous membranes were successfully prepared by electrospinning the zein/HA solution mixed by magnetic stirrer （Method I） or ultrasonic power （Method Ⅱ）. The morphology of zeirdHA nanocomposite fibers and the distribution of HA within the fibers electrospun by two methods were researched by Scanning Electron Microscopy （SEM） and Energy-dispersive X-ray spectroscopy （EDX）. In Method I, the distribution of HA nanoparticles is not homogeneous and HA particles tend to agglom- erate. The relatively homogeneous HA distribution can be observed in the membranes electrospun by Method Ⅱ. Using mag- netic stirrer to prepare the electrospinning solution improves the wettability of zein/HA membranes. From the viewpoint of application, electrospun zein/HA membranes fabricated by the solution mixed via Methods I and II both possessed reasonable tensile strength and elongation at break for both handling and sterilization. Considering two aspects of strength and elongation, electrospun zein/HA membranes fabricated by Method I are more balanced than those fabricated by Method Ⅱ. Biological performances of the control zein and zein/HA membranes were assessed by in vitro culture of hMSCs. Results show that both types of the membranes can support cell proliferation. The cells cultured on the zein/HA membranes electrospun by Method I with 5 wt% HA （on weight ofzein） show significantly higher proliferation than those cultured on the control zein membranes on the seventh day. The electrospun zein/HA fibrous membranes show promises for bone tissue engineering applications.     

Prostaglandin E2 modulates F-actin stress fiber in FSS-stimulated MC3T3-E1 cells in a PKA-dependent manner

The effect of prostaglandin E2（PGE2） on bone mass has been well-established in vivo. Previous studies have showed that PGE2 increases differentiation, proliferation, and regu- lates cell morphology through F-actin stress fiber in statically cultured osteoblasts. However, the effect of PGE2 on osteo- blasts in the presence of fluid shear stress （FSS）, which could better uncover the anabolic effect of PGEz in vivo, has yet to be examined. Here, we hypothesized that PGE2 modulates F-actin stress fiber in FSS-stimulated MC3T3-E1 osteoblastic cells through protein kinase A （PKA） pathway. Furthermore, this PGE2-induced F-actin remodeling was associated with the recovery of cellular mechanosensitivity. Our data showed that treatment with 10 nM dmPGE2 for 15 rain significantly suppressed the F-actin stress fiber intensity in FSS-stimulated cells in a PKA-dependent manner. In addition, dmPGE2 treatment enhanced the cells＇ calcium peak magnitude and the percentage of responding cells in the second FSS stimulation, though these effects were abolished and attenuated by co-treatment with phalloidin. Our results demonstrated that 10 nM dmPGE2 was able to accelerate the ＇reset＇ process of F-actin stress fiber to its pre-stimulated level partially through PKA pathway, and thus promoted the recovery of cellular mechanosensitivity. Our finding provided a novel cellular mechanism by which PGE2 increased bone forma- tion as shown in vivo, suggesting that PGE2 could be a potential target for treatments of bone formation-related diseases.     

纤维桩树脂核修复老年残根残冠的疗效及对炎性因子的影响

目的:探讨纤维桩树脂核修复老年残根残冠的疗效及对炎性因子的影响。方法:抽取2012年1月至2013年4月期间行老年残根残冠修复的患者80例,共92颗患牙,按随机数字表法分为研究组和对照组各40例,其中研究组患牙47颗,采用纤维桩树脂核修复;对照组患牙45颗,采用金属铸造桩核修复。收集两组患者的血清和龈沟液样本,采用酶联免疫吸附法(Enzyme-Linked Immunosorbnent Assay,ELISA)分别检测两组的IL-8、IL-6及TNF-α水平。对比两组疗效及炎性因子水平。结果:研究组治疗患牙总体成功率明显高于对照组,失败率明显低于对照组(P0.05);研究组不同牙位的治疗成功率均较对照组高,但差异不明显(P0.05);修复前两组的IL-8、IL-6及TNF-α的水平差异不明显;研究组修复后1周、1个月及1年的IL-8和IL-6水平均明显低于对照组(P0.05),研究组修复后1年的TNF-α水平明显低于对照组(P0.05),两组患者修复后1周和修复后1月的TNF-α水平相差不大(P0.05);重复测量方差分析结果显示,两组IL-8、IL-6及TNF-α的水平均随着修复时间的延长而降低(P0.05)。结论:纤维桩树脂核修复老年残根残冠具有更好的疗效,对降低牙龈沟液中炎性因子水平的作用明显,值得在临床上应用和推广。     

小干扰RNA沉默瘦素揭示了瘦素在大鼠肝纤维化中的作用

目的观察靶向瘦素(leptin)小干扰RNA(interference,siRNA)真核细胞表达质粒对大鼠肝纤维化的影响。方法采用已构建的重组Leptin-siRNA真核细胞表达质粒,用脂质体包埋法通过腹腔注射将其导入大鼠肝纤维化模型体内。通过HE染色观察肝脏病理形态学变化;Western Blot检测leptin、I型胶原和STAT3蛋白表达变化;半定量RT-PCR检测leptin mRNA表达。结果与正常对照组相比,肝纤维化组(CCl4)和质粒空载体组(CCl4(+)K)肝纤维化程度较重,纤维化评分多为Ⅳ级(P0.01),同时肝脏leptin、I型胶原和STAT3含量明显上升(P0.05);而与肝纤维化组(CCl4)和质粒空载体组(CCl4(+)K)比,leptin-siRNA质粒转染组(The CCl4(+)L)肝纤维化程度减轻,纤维化程度多为Ⅰ-Ⅱ级,肝脏leptin、I型胶原和STAT3表达均显著抑制(P0.05)。正常对照组和leptin-siRNA质粒组(The CCl4(+)L)在组织学及leptin、I型胶原和STAT3基因转录和表达水平无统计学差异(P0.05)。结论 leptin-siRNA表达质粒降低I型胶原和STAT3含量、抑制leptin表达,阻抑肝纤维化;Leptin有望成为肝纤维化基因治疗的新靶位点。     

漆酶／介体体系降解黄麻纤维木质素的研究

为了研究漆酶／介体处理过程中,黄麻纤维木质素结构的变化,采用二氧六环水溶液抽提制取了黄麻纤维木质素,再用漆酶／介体对其处理,通过GPC、元素分析、酚羟基含量测定、红外光谱以及核磁共振氢谱分析了漆酶／介体处理后,黄麻纤维木质素结构的变化。结果表明：经漆酶／介体处理后,黄麻纤维木质素重均分子量和数均分子量减小,酚羟基、醇羟基以及甲氧基含量降低,羰基含量增加。     

生物酶在造纸工业绿色制造中的应用

近年来随着生物技术的发展,生物酶制剂的生产水平不断提高,促进了酶制剂在生物制浆、生物漂白、废纸生物脱墨、酶法纸浆改善性能及树脂生物控制等方面的应用,体现了酶技术在减轻制浆造纸工业环境污染、改善纸浆抄造性能等方面的潜力。文中重点介绍在不同制浆造纸原料及工艺中酶的选用、复配和应用技术及原理,以及酶制剂的应用效率及其对制浆造纸中节能减排和绿色环保的意义。     

元江干热河谷木棉蒴果形成和纤维发育过程

采取石蜡切片和扫描电子显微镜等方法研究了元江干热河谷木棉蒴果形成和纤维发育过程.结果表明: 木棉蒴果形成过程分为4个阶段: 花后0～5 d为形成期(FS),5～35 d为质量增加期(MGS),35～50 d为缓慢生长或脱水期(DS),50 d以后为成熟爆裂期(BS).与木棉蒴果形成过程相对应的纤维发育过程为:果皮内壁细胞分化(花后0～2 d)、膨大(花后2～5 d)、突起(花后5～10 d)、纤维伸长(花后10～40 d)、纤维脱离内壁及脱水成熟(花后40～50 d).在纤维发育过程中,纤维长度和投影宽度均呈幂函数曲线增长,花后第20天日均增长率达到最大.纤维鲜质量呈先增加后下降的趋势,花后25～30 d日均鲜质量增长率达到最高,而纤维干质量呈逐渐增长趋势,且花后20～25 d纤维干质量日均增长率达到最高.花后第30天,木棉种子和纤维质量继续增加,而果皮呈现下降趋势,表明果皮开始脱水老化.木棉纤维在蒴果壳体内壁的附着力小,较棉花等种子纤维更容易分离.花后5～35 d是蒴果生长和纤维发育最关键的时期,需做好水肥管理;而花后50 d后果实开始爆裂,需做好采收准备.     

禽网状内皮组织增生症病毒p30-gp90串联表达蛋白及其免疫原性

摘要:【目的】研究禽网状内皮组织增生症病毒(Reticuloendotheliosis Virus,REV)群特异性抗原P30与囊膜糖蛋白gp90体外共表达蛋白的免疫原性,为研发新型REV 抗体诊断试剂盒提供基础。【方法】根据REV脾脏坏死病毒(spleen necrosis virus,SNV)株的前病毒基因组cDNA序列,设计合成2对引物,以pPB101质粒为模板,分别扩增REV p30基因和gp90基因片段。将PCR产物依次克隆入表达载体pET-28a(+)中,通过酶切鉴定和测序分析,筛选阳性重组克隆pET-p30-gp90。重组菌经异丙基硫代D-半乳糖苷( IPTG)诱导后,通过SDS-PAGE电泳分析表达情况,Western blot检测表达蛋白与特异性血清之间的反应性。制备表达蛋白的抗血清,以该抗血清与REV感染的鸡胚成纤维细胞( CEF)进行间接免疫荧光实验(IFA),验证表达蛋白的免疫原性。【结果】经SDS-PAGE电泳后能观察到预期大小的表达条带,Western blot结果显示,重组蛋白能与REV抗血清反应。将表达产物纯化后免疫Balb/c小鼠,制备p30-gp90抗血清,该抗血清与REV感染CEF在IFA中呈现特异性荧光反应。【结论】体外串联表达REV p30-gp90蛋白,表达蛋白具有良好的免疫原性。