温敏型透明质酸纳米靶向药物传递系统

通过"Click"反应连接透明质酸与普朗尼克F127,制备两亲性材料(HA-F127),其结构通过1H NMR确认,接枝率为13%。材料在水溶液中可自组装形成纳米粒子,并能够包载抗肿瘤模型药物阿霉素。体外药物释放实验显示,其具有温度敏感释药特性。透明质酸可识别肿瘤细胞外过度表达的CD44受体,纳米粒子可靶向传递药物进入肿瘤细胞,且表现出良好的治疗效果。     

雷帕霉素在肿瘤治疗方面研究进展

雷帕霉素(RAPA)在肿瘤治疗方面的研究及应用日益增多,单独应用或联合用药在体外、体内均表现显著的抗肿瘤效果。RAPA通过抑制哺乳动物雷帕霉素靶蛋白(m TOR)受体,影响其转导的多种信号通路,从而发挥抗血管生成、阻滞细胞周期和促进细胞凋亡等多种作用,对肿瘤的增殖、侵袭和转移等过程产生影响。本文综述RAPA在不同肿瘤治疗方面的研究进展,为其在生物医药领域进一步应用提供新方法和新思路。     

脂肪酸多重感知受体及其信号传导研究进展

味觉生理学研究发现，脂肪酸味觉感知可能基于一种新通路，是不同于现有味觉的感知模式。在咀嚼过程中，游离脂肪酸激活味蕾细胞单个或多个受体，触发K+、Ca2+、神经等信号通路，将信号传递至大脑，形成味觉感知。多数情况下，脂肪酸味觉感知是由多重受体共同作用的。脂肪酸经口腔摄入后还会与胃肠道、下丘脑、脂肪组织等受体结合，调节神经递质和食欲激素分泌，引起进食欲望、进食行为及机体能量代谢的改变。本文综述CD36、GPR40、GPR41、GPR43、GPR84、GPR120和CB1/2 7种脂肪酸受体及其介导的信号通路，阐述其在信号传导、代谢调节、免疫应答等方面的作用，并对其应用研究进行展望。     

鞣花酸提取、纯化及其生物活性研究进展

植物界富含多种有益于人体健康的天然物质,并对人体健康起到一定的辅助功能。鞣花酸是一种存在于多种水果与坚果中的天然多酚二内酯,其具有抗氧化、抗炎、抑制细菌生长等多种生物活性,并在癌症治疗和疾病预防方面具有很大的应用潜力。国内外众多学者对鞣花酸生物活性进行深入研究,其在人类疾病、肿瘤治疗以及生产生活中应用前景十分广泛。本文对鞣花酸的提取方法、纯化方法以及抗癌、抗氧化、抗炎等多种生物活性的研究进行了归纳总结,为后续鞣花酸的研究提供一定的参考。     

多糖对免疫系统调控的研究进展

多糖是一类重要的生物信息大分子,广泛存在于动植物和微生物体内。目前,多糖对机体免疫系统的调控作用已获得学术界的普遍认可。多糖对免疫系统的调控机制主要是与免疫细胞表面的模式识别受体如甘露糖受体、Toll样受体、Dectin-1、清道夫受体、补体受体等结合,激活免疫细胞,通过促进单核巨噬细胞的吞噬功能、调控淋巴细胞的增殖和转化、增强对补体系统的活化、诱导细胞因子分泌等实现对机体免疫系统功能的调控。此外多糖对神经-内分泌-免疫系统网络的平衡调控也是其发挥免疫调控作用的重要途径。多糖的生物学活性及其免疫调控作用机制一直以来是国内外科研工作者研究的重要课题。本文主要对近年来国内外对多糖基于免疫系统的免疫调控作用及其机制的研究进行综述。     

透明质酸与磷脂复合物概述

目的　综述透明质酸磷脂复合物的制备方法及其应用。方法　对国内外有代表性的有关文献加以归纳、总结。结果与结论　透明质酸与磷脂可以通过疏水键、共价键等结合形成复合物,与单独服用透明质酸相比对关节疾病等的疗效显著提高。     

抗肿瘤活性肽的研究进展

抗肿瘤生物活性肽与化疗药物相比,具有毒性低、特异性强、不易形成耐药性等优点,已经成为抗肿瘤新药研究的热点。本文从近十多年来国内外对抗肿瘤活性肽的应用研究着手,对抗肿瘤活性肽的天然来源及制备技术、构效关系、抗肿瘤作用机制等进行综合阐述,并指出了其在肿瘤治疗中的发展优势和可能存在的问题。     

透明质酸的微生物发酵法生产与应用概况的探析

<正>透明质酸简述透明质酸是一种酸性粘多糖,美国的教授Meyer等在1934年在牛眼玻璃体中首先分离出了透明质酸。透明质酸有着其他物质没有的理化性质和分子结构,这就使透明质酸可以应用在不同的方面,也使透明质酸在各个领域的应用越来越广泛,如对蛋白质进行调节、水电解质的扩散、促使创伤愈合等等。透明质酸在人体中的含量的变化会随着人类皮肤的老化程度的变化而变化,透明质酸的存在会改善皮肤的代谢,可以使     

膳食纤维调节糖尿病降血糖作用的研究进展

膳食纤维对糖尿病患者的预防和治疗具有重要的临床意义,目前糖尿病已经比心血管疾病、肿瘤等慢性疾病更为引起人类的重视,其严重威胁着人类健康,糖尿病的治疗变得越来越迫在眉睫,膳食纤维被证明在血糖控制方面具有显著的作用,很多的临床研究对此进行了试验证明,但是目前膳食纤维的降糖机理还尚待完善,主要的机理包括作用于糖代谢的机理和作用于胰岛素的机理研究,因此需要进一步的研究来证明。本文综述了膳食纤维对糖尿病的预防及治疗资料,包括膳食纤维的定义、结构、功能、膳食纤维的降糖机理、膳食纤维对糖尿病的临床治疗实例等,通过从不同的方面对膳食纤维的降糖作用进行总结,希望为膳食纤维的功能性食品开发和资源的综合利用提供一些理论依据。     

低分子量透明质酸功能与制备研究进展

透明质酸广泛应用于医药、化妆品和食品等领域,目前主要通过微生物发酵生产。透明质酸的生物活性和使用效果与其相对分子量相关。近年来,低分子量透明质酸在抗肿瘤、促进伤口愈合与血管生成、免疫调节、药物靶向等方面具有重要潜在应用价值,引起了人们的广泛关注。本文针对低分子量透明质酸生物活性功能以及制备方法等方面的研究进展进行了综述。     

The effect of glycosaminoglycans on rat gametes in vitro and the associated signal pathway

The effects of adding the extracellular glycosaminoglycans (GAGs), hyaluronic acid (HA) and chondroitin sulphate (CS) to rat in vitro fertilisation (IVF) media were assessed. Metaphase II (MII) oocytes were also incubated in GAG-supplemented modified rat 1-cell embryo culture medium (mR1ECM+BSA) for 3 days. Cytoplasmic fragmentation was significantly reduced in mR1ECM+BSA with HA (39.0-48.0%) compared with the control (82.0%). In IVF experiments, neither HA (8.0-30.8%) nor CS (9.7-42.5%) improved fertilisation rates compared with controls fertilised in M16 (47.2%) or enriched Krebs-Ringer bicarbonate solution (61.5%). RT-PCR and Western blot were used to probe for CD44 mRNA and protein in Sprague-Dawley gametes and cumulus cells. CD44 was identified in cumulus cells, suggesting a role for oocyte maturation and cumulus expansion. The CD44 protein was also present on caudal epididymal spermatozoa that were highly stimulated by CS in vitro implicating a role in fertilisation for CS and CD44.     

Microbial synthesis of hyaluronan and chitin: New approaches

Hyaluronan (HA) is an important structural element in the vitreous humor of the eye, synovial fluid, and skin of vertebrates. Moreover, HA interacts with proteins such as CD44, RHAMM, and fibrinogen, thereby influencing many natural processes such as angiogenesis, cancer, cell motility, wound healing, and cell adhesion. Reflecting such a variety of functions, HA has attracted attention from a wide range of application fields such as medicine (including surgery), cosmetics, and health foods. Traditionally HA was extracted from rooster combs, but nowadays is produced by the fermentation of streptococci. At present, quality issues such as purity and molecular weight distribution, rather than quantity, have been the focus of strain and process development in HA production. To meet ever-increasing public demand, novel systems that can yield sufficient amounts of high-quality of HA and related materials are required.     

No Influence of Exogenous Hyaluronan on the Behavior of Human Cancer Cells or Endothelial Cell Capillary Formation

Hyaluronan (HA), a type of glycosaminoglycan used to construct the extracellular matrix, is involved in the proliferation and motility of cells, including cancer cells. The aim of this study was to determine whether exogenous HA has an influence on cancer in vitro and in vivo. High‐molecular‐weight HA (900 kDa) and low‐molecular‐weight HA (10 kDa) were added to several types of cancer cell lines in vitro, and proliferation and invasion were assessed. The effect of HA on capillary formation by human umbilical vein endothelial cells was also analyzed. The results showed that both types of HA had no apparent effect on cellular proliferation, invasion, or capillary formation. In an animal study, the 2 types of HA were orally administered to tumor‐bearing mice at a dosage of 200 mg/kg/d for 4 wk. Analysis using an in vivo imaging system revealed that tumor proliferation and metastasis were not greatly altered by HA administration. Furthermore, CD31 immunohistochemical staining revealed no obvious change in tumor microvessels. Taken together, these results demonstrate that exogenously administered HA has little effect on cancer. This study may support the safety of various forms of HA administration, including oral intake.     

Immobilizing humic acid in a sol-gel matrix: a new tool to study humic-contaminants sorption interactions

Humic substances originated from aquatic, soil, or sediment environments are mixtures of humic compounds with various characteristics. Sorption interactions with isolated, well defined humic fractions can be studied either in an aqueous phase ("dissolved humic substances"), or in a solid-phase, by coating mineral particles with the humic materials, or simply by working with humic acid particles (powder) at low pH to minimize dissolution. Each attitude, by definition, can be studied by different experimental techniques and has a different meaning for understanding natural environmental processes. In this study, a new tool for studying sorption interactions is presented. Sol-gel was used as an inert matrix to immobilize (entrap) various humic acids (HAs), and then used to study the interactions of several polycyclic aromatic hydrocarbons (PAHs) with the entrapped HA. Linear and nonlinear sorption coefficients were highly correlated with contaminant hydrophobicity. Sorption of pyrene to immobilized HA was in the order of soil HA > Aldrich HA approximately = peat HA. It was concluded that the entrapped HAs retained their original properties in the gel matrix and were accessible to the external contaminant through the pore network. Additionally, binding coefficients of pyreneto dissolved humic substances and to dissolved organic matter (DOM) were determined from the reduction in pyrene sorption to immobilized HA in the presence of dissolved humic material or DOM in solution. Binding coefficients of pyrene were in the order of the following: dissolved Aldrich HA > dissolved peat fulvic acid (FA) > DOM derived from mature compost > DOM derived from fresh compost.     

Application of saturation transfer double difference NMR to elucidate the mechanistic interactions of pesticides with humic acid

Elucidation of mechanistic interactions of anthropogenic chemicals is critical to understanding and eventually predicting their behavior in the environment Here, a recently developed technique, saturation transfer double difference (STDD) NMR spectroscopy is employed to determine the interactions of pesticides with humic acid (HA) at the molecular level. The degree of interaction at each NMR observable nucleus in the pesticide can be quantified in the form of an epitope map, which depicts the mechanism of the pesticide-HA interaction. Our results indicate that, at pH 7, halogen atoms (F and Cl) in water-soluble pesticides (diflufenzopyr, acifluorfen, and chlorsulfuron) play a dominant role in influencing binding to HA, whereas carboxyl groups likely play a secondary role when halogen atoms are also present in the molecule, as observed with diflufenzopyr and acifluorfen. However, when present on its own, the carboxyl group dominates in binding affinityto HA (e.g., imazapyr). Electronegativity and electron density appear to play a key role in the mechanism of binding and results suggest that polar bonds are the primary points of HA contact in the water soluble pesticides investigated. Likely interactions may include hydrogen bonding and dipole-dipole interactions.     

Localization of CD9 in pig oocytes and its effects on sperm-egg interaction

CD9 is a cell surface protein that participates in many cellular processes, such as cell adhesion. Fertilization involves sperm and oocyte interactions including sperm binding to oocytes and sperm-oocyte fusion. Thus CD9 may play an essential role during fertilization in mammals. The present study was conducted to examine whether CD9 is present in porcine gametes and whether it participates in the regulation of sperm-oocyte interactions. The presence of CD9 in ovarian tissues, oocytes and spermatozoa was examined by immunohistochemistry, immunofluorescence and immunoblotting. Sperm binding and penetration of oocytes treated with CD9 antibody were examined by in vitro fertilization. The results showed that CD9 was present on the plasma membrane of oocytes at different developmental stages. A 24 kDa protein was found in oocytes during in vitro maturation by immunoblotting and its quantity was significantly (P < 0.001) increased as oocytes underwent maturation and reached the highest level after the oocytes had been cultured for 44 h. No positive CD9 staining was found in the spermatozoa. Both sperm binding to ooplasma and sperm penetration into oocytes were significantly (P < 0.01) reduced in anti-CD9 antibody-treated oocytes (1.2 +/- 0.2 per oocyte and 16.6% respectively) as compared with oocytes in the controls (2.5 +/- 0.4 per oocyte and 70.3% respectively). These results indicated that CD9 is expressed in pig oocytes during early growth and meiotic maturation and that it participates in sperm-oocyte interactions during fertilization.     

Monitoring the effect of three humic acids on a model membrane system using 31P NMR

The sorption of three humic acids to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine multilamellar vesicle model membrane systems was studied by phosphorus nuclear magnetic resonance (31P NMR). The effects of temperature and pH were investigated. The gel --> bilayer transition did not appear to be affected by any of the humic acids at pH 7; however, all three humic acids induced a perturbation to this transition and to the bilayer structure at pH 4. On the basis of the findings from this and other work, a conceptual adsorption/absorption model for the sorption of humic acid (HA) to biomembranes has been put forward. The model requires an initial adsorption step initiated at an acidic pH by hydrogen bridging and electrostatic interactions between the functional groups of the HAs and the head groups of the phospholipids. Once the HA material is adsorbed, its hydrophobic domains can further seek a more thermodynamically favorable environment within the bilayer using hydrophobic interactions. These interactions lead to the HA being absorbed into the membrane, which subsequently induces the observed perturbation by disturbing the ordered packing of the phospholipid tail groups. This model is also related to other humic substances/biomembrane observations in the literature.     

Copolymerization of lactic acid for cost-effective PLA synthesis and studies on its improved characteristics

The present study involves synthesis of polylactic acid (PLA) using purified lactic acid from fermented broth of Jackal jujube (Zizyphus oenophlia). A polyphenolic compound, humic acid (HA) of biological origin was incorporated to the PLA in order to reinforce the PLA chain without compromising its biodegradability and biocompatibility. Under optimized conditions of polymerization, modified L-PLA yield improved up to 93%. The molecular weight was found to be 6.4×10⁵. Different physicochemical properties of the polymer were explored for its further application in different fields. Incorporation of intermolecular bond between PLA and HA was confirmed by FT-IR spectroscopy technique. Addition of HA not only reduced the crystallinity of PLA, but also had increased flexibility and elasticity to much greater extent. The results showed that, apart from enhancing the physicochemical properties of PLA, the process also had reduced the production cost of the polymer, while mitigating the demands of environmental protection agencies.     

多酚-蛋白质共价作用及其对食品体系的影响研究进展

近年来多酚与蛋白质间的相互作用及其对食品体系的影响受到人们的极大关注。按作用方式可将多酚与蛋白质之间的相互作用分为非共价作用和共价作用。有关非共价作用的研究较完善,相比之下共价作用的研究报道非常少。为推动对食品体系中多酚与蛋白质共价作用的研究,在广泛查阅文献的基础上,本文综述了多酚与蛋白质共价结合的机理、影响因素以及这种结合对食品体系感官特性、功能与营养特性、安全性的影响,并进一步提出了有关食品体系中多酚与蛋白质共价作用今后的研究方向。