南极细菌Pseudoalteromonas sp.S-15-13的分子鉴定及其胞外多糖促进小鼠脾淋巴细胞转化的作用

目的探讨产胞外多糖南极细菌的筛选,对高产糖菌株S-15-13进行分子鉴定,并测定其胞外多糖的体外免疫活性。方法采用显微镜检测以及细菌胞外多糖染色方法对南极产糖菌进行了筛选;通过16S rDNA对菌株S-15-13进行了分子鉴定并采用Heek方法测定了该菌胞外多糖促进小鼠脾淋巴细胞增殖的作用。结果与结论从南极科学考察采集、分离的57株细菌中,通过胞外多糖染色法筛选获得27株产胞外多糖的菌株,16SrDNA鉴定菌株S-15-13为Pseudoalteromonassp.。胞外多糖分离、纯化后获得的组分Ⅰ(EPSⅠ)单独或联合Con A使用可明显促进脾淋巴细胞增殖。     

pH-敏感型水凝胶在多肽和蛋白质药物给药系统研究中的应用

目的:介绍pH-敏感型水凝胶在多肽和蛋白质药物给药系统研究中的应用.方法:检索分析文献资料,并进行综合、整理与归纳.结果:综述了pH-敏感型水凝胶用作多肽和蛋白质药物给药系统在材料选择、制作方法、具体应用研究等方面的进展.结论:pH-敏感型水凝胶非常适合用作多肽和蛋白质药物给药系统,值得并有待进行广泛和深入的研究.     

利多卡因表面分子印迹聚合物的制备及其吸附特性研究

目的 采用分子印迹技术制备利多卡因二氧化硅表面分子印迹聚合物,探究其吸附特性,用于选择性吸附、富集利多卡因。方法 利用分子印迹技术,以利多卡因为模板分子,通过溶胶-凝胶法制备利多卡因二氧化硅表面分子印迹聚合物,并通过静态吸附平衡试验、动态吸附试验、扫描电镜、红外光谱研究聚合物的吸附特性、结构及形貌特征。结果 与化学组成相同的非印迹聚合物相比,印迹聚合物具有良好的吸附性。结论 将该印迹聚合物用于选择性吸附、富集利多卡因是可行的。     

南极细菌Pseudoalteromomas sp.S-15-13的分子鉴定及其胞外多糖促进小鼠脾淋巴细胞转化的作用

目的探讨产胞外多糖南极细菌的筛选，对高产糖菌株S-15—13进行分子鉴定。并测定其胞外多糖的体外免疫活性。方法采用显微镜检测以厦细菌胞外多糖染色方法对南极产糖菌进行了筛选；通过16SrDNA对菌株S-15—13进行了分子鉴定并采用Heek方法测定了该菌胞外多糖促进小鼠脾淋巴细胞增殖的作用。结果与结论从南极科学考察采集、分离的57株细菌中．通过胞外多糖染色法筛选获得27株产胞外多糖的菌株，16SrDNA鉴定菌株S-15—13为Pseudoalteromonas sp．。胞外多糖分离、纯化后获得的组分Ⅰ（EPSⅠ）单独或联合Con A使用可明显促进脾淋巴细胞增殖。     

环孢素A眼用pH敏感型乳剂凝胶的角膜滞留性及药效学

目的:制备环孢素A眼用pH敏感型乳剂凝胶并研究其角膜滞留性及药效学。方法:以家兔为模型动物,环孢素A眼用乳剂为对照组,利用γ-闪烁扫描技术考察环孢素A眼用pH敏感型乳剂凝胶的眼部滞留性;并建立干眼症模型,以泪液分泌实验(schirmer I test,SIT)和角膜荧光素染色(fluorescence integral,FI)值为指标,结合外观评价,考察环孢素A眼用pH敏感型乳剂凝胶治疗干眼症的效果。结果:环孢素A眼用pH敏感型乳剂凝胶与对照组相比,显著延长在角膜的滞留时间;利用SPSS 19.0统计分析软件显示:实验组与阳性对照组在增加SIT值方面有极显著性差异(P<0.01),在降低FI值方面有显著性差异(P<0.05)。结论:环孢素A眼用p H敏感型乳剂凝胶显著延长在角膜的滞留时间,对干眼病的治疗起效更快,治疗效果更好。     

氧化还原敏感型靶向纳米给药系统的研究进展

理想的肿瘤靶向给药系统应在肿瘤部位高度累积且快速释放药物,而在血液循环中无泄漏,利用肿瘤环境改变的氧化还原状态及细胞内外的谷胱甘肽差异,结合纳米给药系统,可实现精准肿瘤靶向。本文对氧化还原敏感型靶向纳米给药系统的原理、氧化还原敏感键及其构建方法进行了介绍,并对基于脂质体、纳米粒、纳米胶束、纳米凝胶4种载体的不同氧化还原敏感型纳米给药系统在肿瘤靶向治疗中的应用进行了分析和总结,可为肿瘤靶向给药的进一步研究提供参考。     

温度敏感型聚酯/聚乙二醇三嵌段生物可降解共聚物的降解性能及药物释放的影响因素研究进展

温度敏感型生物可降解水凝胶作为一种注射缓释给药系统的新型载体己受到越来越多的关注,聚酯(A嵌段)/聚乙二醇(B嵌段)三嵌段共聚物是目前最常用的温度敏感型聚合物,具有良好的生物相容性和生物降解性.本文综述了聚乙二醇嵌段含量、聚酯嵌段种类、共聚物凝胶水溶液浓度、处方中添加剂、药物与共聚物分子间的作用力、载药量及制剂形状、介质pH及温度等因素对聚酯/聚乙二醇三嵌段共聚物降解速率及药物释放速率的影响,为聚酯/聚乙二醇三嵌段共聚物水凝胶注射剂开发过程中共聚物降解速率和药物释放速率的调节提供有价值的思路与科学依据.     

1,3-二羟基丙酮的分离提取研究进展

1,3-二羟基丙酮(1,3-dihydroxyacetone,DHA)是一种简单酮糖,作为甘油的高附加值产物,在医药、化工领域有广泛的应用前景。微生物发酵生产DHA的方法以其反应条件温和、底物利用率高、副产物少、工艺简单、易于控制等优点成为了目前国内外生产DHA应用的主要方法,但由于DHA在水溶液中溶解度极大,对热极其敏感等特性导致其分离提取成本高、能耗大,成为了工业生产上的一大难题。该文介绍了1,3-二羟基丙酮生产过程中产物分离提取的研究现状和技术开发进展。对以甘油为原料,微生物发酵法制备DHA的研究进行了展望。     

刀豆蛋白A对小鼠肝线粒体结构和功能的影响

目的研究刀豆蛋白A(Con A)致小鼠免疫性肝损伤时,肝线粒体结构和功能的改变。方法C57BL/6J小鼠随机分为正常对照组、Con A 10和20 mg·kg~(-1)组,分别尾静脉注射灭菌生理盐水、Con A 10和20 mg·kg~(-1),给药8 h后,测定血清谷丙转氨酶(GPT)活性和肝组织病理变化。通过检测血清谷氨酸脱氢酶(GDH)活性评价线粒体膜通透性的改变,用透射电镜观察肝细胞线粒体结构,用高效液相色谱(HPLC)测定肝组织匀浆液中ATP,ADP和AMP含量,计算肝总腺苷酸库(TAN)及能荷水平(AEC),评价线粒体功能状态。结果与正常对照组比,Con A 10和20 mg·kg~(-1)组小鼠血清GPT和GDH活性均显著升高(P<0.05,P<0.01)。用透射电镜观察发现,肝细胞线粒体膜结构破坏,线粒体肿胀,形状高度不规则。功能学研究表明,小鼠肝组织中ATP含量分别降低了25.6%和38.3%(P<0.01),ADP含量分别降低了36.0%和47.1%(P<0.01),TAN水平分别降低了16.5%和18.9%(P<0.05),AEC分别降低了15.7%和28.1%(P<0.01)。结论 Con A免疫性肝损伤与肝细胞线粒体膜通透性增加、肝细胞线粒体结构完整性破坏、生成高能磷酸化合物能力下降和肝细胞能量储备减少有关。     

α-细辛脑纳米粒离子敏感型鼻用原位凝胶的制备及体外释药性能

目的:制备α-细辛脑纳米粒离子敏感型鼻用原位凝胶并考察其体外释放行为。方法:采用去乙酰结冷胶(DGG)为凝胶基质,以凝胶黏度,形成凝胶的能力及持水力为考察指标筛选去乙酰结冷胶的用量;采用纳米沉淀法制备α-细辛脑纳米粒,与凝胶基质混合后制得α-细辛脑纳米粒离子敏感型原位凝胶;以人工模拟鼻液为释放介质、考察制剂的体外释放特性。结果:确定0.5%的结冷胶作为α-细辛脑纳米粒离子敏感型原位凝胶的基质,在非生理状态为自由流动的液体,生理状态下能够发生相变形成凝胶。体外释放结果表明α-细辛脑纳米粒离子敏感型鼻用原位凝胶具有较好的缓释作用。结论:α-细辛脑纳米粒离子敏感型原位凝胶的胶凝效果良好,缓释作用明显且制备工艺简单可行。     

Insulin delivery governed by covalently modified lectin-glycogen gels sensitive to glucose

A glucose-sensitive gel formulation containing concanavalin A and glycogen has been reported previously. Precipitation resulting from the addition of concanavalin A to glycogen has been documented, but the formation of glucose-sensitive gels based on lectin-glycogen interactions is novel and used here in our studies. An improved in-vitro self-regulating drug-delivery system, using covalently modified glucose-sensitive gels based on concanavalin A and a polysaccharide displacement mechanism, is described. The successful use of the covalently modified gels addresses a problem identified previously where significant leaching of the mitogenic lectin from the gel membranes of non-coupled gels was encountered. Concanavalin A was covalently coupled to glycogen by use of derivatives of Schiff's bases. The resulting gels, like the non-coupled gels, were shown to undergo a gel-sol transformation in response to glucose. Insulin delivery was demonstrated using this covalently modified system in conditions of repeated glucose triggering at 20 degrees C and 37 degrees C. The magnitude of the response was less variable than for the dextran-based gels studied previously. The performance of this system has been improved in terms of concanavalin A leaching. This could, therefore, be used as the basis of the design of a self-regulating drug-delivery device for therapeutic agents used to treat diabetes mellitus.     

Characterization of Glucose Dependent Gel-Sol Phase Transition of the Polymeric Glucose-Concanavalin A Hydrogel System

Purpose. The main goal of this study was to synthesize and characterize hydrogels which undergo reversible gel-sol phase transformation in response to changes in glucose concentration in the surrounding environment. Methods. The glucose-sensitive hydrogels were made by mixing the appropriate concentrations of acrylamide-allyl glucose copolymer and concanavalin A (Con A). To examine their phase reversibility, hydrogels in dialysis membranes were cycled between glucose-free and glucose-containing buffers. The binding affinity of allyl glucose (AG) to Con A was examined by using an equilibrium dialysis technique. Results. The synthesized hydrogels underwent phase transition to sol in the presence of free glucose in the environment. The concentration of external free glucose (C_f) had to be at least 4 times that of polymer-bound glucose (C_p) to induce phase transition from gel to sol. The binding affinity study showed that binding of AG to Con A was four times stronger than that of free glucose. When C_p in the gel was 0.42 mg/ml or higher, C_f had to be much higher than 4 times C_p to induce phase transition. Conclusions. The synthesized hydrogels underwent phase transition in the presence of free glucose in the environment, but the phase transition was not linearly dependent on the concentration of free glucose. This non-linear dependence was explained by the increased binding affinity of AG over native glucose to Con A, and the cooperative interactions between polymer-bound glucose and Con A.     

Phenylboronic acid grafted chitosan as a glucose-sensitive vehicle for controlled insulin release

To develop self-regulated insulin delivery system, the glucose-sensitive copolymers with a fraction of phenylboronic acid group were prepared by the coupling reaction of -COOH of N-(carboxyacyl) chitosan and -NH(2) of 3-aminophenylboronic acid. A sufficient glucose sensitivity of the copolymer was accomplished by the glucose-induced volume changes of the nanoparticles and release profiles of insulin in phosphate buffered saline (PBS, pH 7.4) with different glucose concentrations, which occurred in a remarkable glucose concentration-dependent manner. Furthermore, circular dichroism spectroscopy demonstrates that the overall tertiary structure of the released insulin was not altered compared with that of the standard insulin. The analysis of relative cell proliferation suggests that the copolymer showed good cytocompatibility. The glucose-sensitive copolymers have a potential use in self-regulated drug-releasing systems.     

Covalent coupling of concanavalin A to a Carbopol 934P and 941P carrier in glucose-sensitive gels for delivery of insulin

A novel glucose-sensitive gel formulation, containing concanavalin A and specific polysaccharides, was stabilised via covalent coupling to two structurally different carbomers. The bonding was done to minimise leaching of gel components thereby preventing toxicity and preserving the working mechanism of the gel. Increased gel stability was introduced by covalently bonding amine groups present on the lysine residues of concanavalin A to carboxylic moieties on Carbopol 934P NF and 941P NF using carbodiimide chemistry. The introduction of dextran then produced a glucose-sensitive formulation that transformed from gel to sol in the presence of free glucose. Rheological examination of glucose-sensitive gels stabilised in this way and containing varying concentrations of glucose was conducted with a cone and plate viscometer used in continual rotation mode. A decrease in viscosity over the chosen glucose concentration range was exhibited by both carbomer-stabilised formulations. The subsequent testing of such formulations in in-vitro diffusion experiments revealed that the leaching of concanavalin A from the covalently coupled gels is restricted significantly with respect to non-coupled formulations. In addition, insulin delivery in response to glucose in the physiologically relevant glucose concentration range has been demonstrated using the carbomer-stabilised gels at 37 degrees C. The performance of this self-regulating drug delivery system has been improved in terms of increased gel stability with reduced component leaching.     

Inhibition of interleukin-2 production and lymphocyte responsiveness by the cell activation inhibitor, CI-959.

CI-959 (5-methoxy-3-(1-methylethoxy)-N-1H-tetrazol-5-yl-benzo [b]-thiophene-2-carboxamide), an antiallergy compound, blocked release of IL-2 from Con A stimulated rat splenocytes and human lymphocytes with respective IC50s of 19.1 and 23.1 microM. Inhibition of IL-2 production required the presence of CI-959 in culture medium for the first 9 hr. CI-959 also inhibited Con A-stimulated rat and human lymphocyte proliferation with IC50s of 4.7 and 5.4 microM, respectively. Inhibition of the Con A proliferative response could not be overcome by exogenous recombinant human IL-2 (300 units/ml) in either the rat or human systems. Although potent in the human mixed lymphocyte reaction (IC50 = 3.5 microM), CI-959 was less effective in blocking the PHA response (IC50 = 43.9 microM), and had minimal effect on the release of IL-1 and TNF alpha from LPS-stimulated human monocytes. These findings suggest that CI-959 selectively inhibits some lymphocyte functions, as opposed to monocyte functions, and that among these is the production of IL-2.     

Effect of concanavalin A on intracellular calcium concentration in single blood platelets.

Mobilization of Ca++ was estimated in single rabbit blood platelets with digital imaging microscopy. Concanavalin A (Con A) caused a rapid initial increase in intracellular concentration of Ca++ ([Ca++]i) with a latent time of about 20 sec, followed by a sustained increase in [Ca++]i. This effect of Con A was antagonized by alpha-methyl-D-mannose, which already was shown to antagonize the inhibitory effect of Con A on 5-HT transport, indicating that this effect of Con A was also derived from its binding to cell surface glycoproteins. The presence of EGTA in the medium did not affect the initial rise, but inhibited the latter phase of sustained rise. Thus, Con A induced elevation of [Ca++]i was suggested to consist of two different processes: mobilization of Ca++ from the intracellular storage sites and successive Ca++ influx through Ca++ channels. The effect of Con A on the 5-HT transport was tested in the presence of EGTA, a condition where no Ca++ influx occurs. The results indicate that Con A induced inhibition of 5-HT transport was not influenced by EGTA in the medium. It is suggested that the effect of Con A on 5-HT transport might be exerted through the Ca++ mobilization from its intracellular storage sites.     

水凝胶作为胰岛素控释系统载体的研究进展

从靶向、定位和葡萄糖敏感型控释给药系统等方面介绍水凝胶作为胰岛素载体的研究进展.     

Effects of concanavalin A on 5-hydroxytryptamine uptake by rabbit blood platelets and on their ultrastructure.

1. Effects of concanavalin A (Con A) and other lectins on 5-hydroxytryptamine (5-HT) uptake by rabbit blood platelets and on their ultrastructure were studied. 2. Uptake of [3H]-5-HT by platelets was decreased by application of Con A, E-PHA (lectin from Phaseolus vulgaris) and lentil-PHA (lectin from Lens culinaris), but not by wheat germ agglutinin (WGA). Con A induced specific changes in the ultrastructure of platelets, causing (i) a change in external appearance from a discoid to an irregularly spherical shape, (ii) re-arrangement of the canalicular system and formation of a concentric structure. These effects of Con A on platelets were antagonized by pretreatment with alpha-methyl-D-mannoside (alpha-MM), a specific inhibitor of Con A binding to glycoprotein. 3. The inhibition of 5-HT uptake by Con A was antagonized by colchicine, vinblastine and sodium nitroprusside (SNP), but not by cytochalasin B. 4. Theophylline, papaverine and dibutyryl cyclic adenosine 3',5'-monophosphate (db cyclic AMP) antagonized the effect of Con A on 5-HT uptake, but dibutyryl cyclic guanosine 3',5'-monophosphate had no effect. Theophylline and db cyclic AMP did not influence the effect of Con A on the ultrastructure of platelets. 5. It is suggested that binding of Con A to specific receptor glycoproteins can inhibit the 5-HT uptake system of platelets. Microtubules, contractile protein and the membrane adenylate cyclase system of platelets may also be regulatory factors in this mechanism.     

Macrophage-mediated killing of splenic lymphocytes in adjuvant-induced arthritis.

After 72 hrs in culture, unseparated spleen cells from rats with adjuvant-induced arthritis (AA) stimulated with high concentrations of Con A (greater than 0.63 micrograms/ml) leaked more lactate dehydrogenase (LDH) than did either unstimulated cultures or cultures stimulated with lower concentrations of Con A. This reflects an increase in dead or dying cells at concentrations of Con A greater than 0.63 micrograms/ml. Since Con A did not increase LDH leakage in macrophage-depleted cultures of AA splenocytes, the decreased viability in unseparated, Con A-stimulated cultures appears to be a macrophage-dependent phenomenon. Since the increase in LDH release at high concentrations of Con A paralleled the decrease in [3H]-thymidine incorporation, these results suggest that Con A (greater than 0.63 micrograms/ml) induces macrophages from AA rats to kill splenic lymphocytes in culture.     

Glucose-Binding Property of Pegylated Concanavalin a

Purpose. Concanavalin A (Con A) has been used in the development of sol-gel phase-reversible hydrogels for modulated insulin delivery. The usefulness of Con A has suffered from its poor aqueous solubility and stability. The goal of this study was to modify Con A with poly(ethylene glycol) (PEG) and examine the water solubility and stability of the PEGylated Con A. Methods. Con A was PEGylated using monomethoxy poly(ethylene glycol) p-nitrophenol carbonates, and the extent of PEGylation was determined by the fluorescamine method. The stability of the PEGylated Con A was examined by measuring the time-dependent absorbance at 630 nm. The binding affinities of glucose and allyl glucose to native- and PEGylated-Con A were measured by the equilibrium dialysis method. Results. The total number of PEG molecules that can be grafted to Con A was 10. As the number of grafted PEG chains per each Con A was increased up to 5, the binding affinity of glucose was gradually increased and reached the maximum. The solubility and stability of PEGylated Con A were improved significantly over those of native Con A. The binding affinity of allyl glucose to Con A was not changed much by PEGylation. When the extent of PEGylation was excessive (i.e., the number of grafted PEG chains per each Con A was larger than 5), however, the binding affinities of both glucose and allyl glucose were decreased significantly. Conclusions. PEGylation of Con A resulted in improved aqueous solubility and stability of Con A. The binding affinity of glucose increased and reached the maximum when the extent of PEGylation was 50%. Advantages of PEGylated Con A over native Con A are improved aqueous solubility, enhanced long-term stability, and higher glucose sensitivity.