1000/胸腺五肽缓释微球的制备及性能的研究

目的：通过胸腺五肽（TP5）缓释微球的制备研究,为TP5缓释制剂的研究提供科学依据。方法：以聚乳酸-羟基乙酸共聚物（PLGA）为包裹材料,采用复乳法制备TP5-PLGA缓释微球,通过扫描电镜观察了微球的形态,对微球的载药量、包封率及体外释药情况进行了研究。HPLC测试条件为： 色谱柱：Kromasil C18, 5 µm, 250×4.60 mm,流动相：15%乙腈（含0.1%TFA）,流速：1.5 ml/min,检测波长：222 nm。结果：制备的微球表面光滑,球体均匀;微球中TP5的载药量和包封率分别为1.87%和67%左右;微球在10天内具有良好的释药性能。结论：TP5-PLGA缓释微球具有明显的缓释作用。     

替莫唑胺-PLGA纳米缓释微球的制备及体外药效研究

目的制备理想的可用于控制胶质瘤细胞生长进而可抑制胶质瘤的替莫唑胺-PLGA纳米缓释微球。方法用超声乳化-溶剂挥发法制备替莫唑胺-PLGA纳米缓释微球。选择测试了四种不同分子量的缓释微球的表面形态特征,并测量微球直径。检测载药量和包封率,分析制作参数、形态特征以及绘制释放曲线。结果替莫唑胺-PLGA缓释微球是一种结构稳定、大小均匀的缓释微球。分子量越大,微球直径越大。高分辨光镜及电镜观察,微球表面光滑,无裂隙,微球无明显聚集,微球大小均匀。不同分子量的TMZ-PLGA缓释微球最大载药量为10.2%,包封率都在90%以上。二氯甲烷残留量为5.70‰,达到了颅内安全应用的要求。从释放曲线可以看出,缓释系统中替莫唑胺可以持续释放2周以上,符合间质内化疗所要求的周期。结论 PLGA非常适合作为制备缓释微球的缓释载体。所制备的替莫唑胺-PLGA缓释微球符合生物力学规律,替莫唑胺虽有突释效应,但药物缓释时间可控。不同分子量及不同载药量的缓释微球均能长时间持续释放替莫唑胺。     

心肌内双层多孔生物可降解性药物缓释支架的制备**☆◆

目的：制备心肌内双层多孔生物可降解性药物缓释支架，评估其对透室壁性心肌血管重建术后心肌孔道的作用效果。 方法：以聚己内酯为材料，以牛血清白蛋白为模型药物，以聚乳酸-聚乙醇酸共聚物为药物载体，制备成生物可降解性药物缓释支架。采用考马斯亮蓝试剂法对支架上牛血清白蛋白含量及体外释放量进行测定，万能材料测定仪测定支架的力学性能。制备猪慢性心肌局部缺血模型，体内评估该支架在透室壁性心肌血管重建术后对心肌孔道的作用效果。 结果：该支架牛血清白蛋白携带量为每支架 10 mg，30 d后牛血清白蛋白释放量达80%，支架压缩80%时承受的应力为1.2 MPa，在透室壁性心肌血管重建后可保持心肌孔道通畅。 结论：成功制备心肌内双层多孔生物可降解性药物缓释支架，能承受心肌压力并达到缓慢控制释放药物的效果，可维持透室壁性心肌血管重建后的心肌孔道通畅。     

三维支架材料与脂肪干细胞的生物相容性

背景：构建组织工程化气管需要适合的三维支架。 目的：观察脂肪干细胞与聚乳酸-乙醇酸共聚物及聚三亚甲基碳酸酯共聚物支架的生物相容性。 方法：采用组织块法原代分离培养SD大鼠脂肪干细胞,行流式细胞术及多向分化能力鉴定。将脂肪干细胞分别种植于聚乳酸-乙醇酸共聚物和聚乳酸-乙醇酸-三亚甲基碳酸酯共聚物支架中,扫描电镜观察细胞与支架的生物相容性。 结果与结论：脂肪干细胞种植于两种支架材料后生长速度快,扫描电镜观察可见脂肪干细胞呈球型,并伸展形成伪足,贴附于支架材料,细胞间相互连接成团。说明聚乳酸-乙醇酸共聚物与聚三亚甲基碳酸酯共聚物支架均具有良好的生物相容性,无细胞毒性,其多孔的三维立体状结构适合脂肪干细胞黏附生长。     

单因素试验筛选缓释碱性成纤维细胞生长因子微球的制备条件

背景：研究表明，缓释碱性成纤维细胞生长因子微球制备工艺条件影响因素多，筛选工作费时费力，且工艺的重现性较差。 目的：以碱性成纤维细胞生长因子包封率为指标，应用单因素设计，初步考察碱性成纤维细胞生长因子缓释微球制备基本工艺条件。 设计、时间及地点：单因素设计实验，于2005-03/05在中国科学院成都有机化学研究所高分子实验室完成。 材料：以相对分子质量2.0万聚乳酸-羟基乙酸共聚物为载体材料，选用W/O/W复乳-干燥法制备碱性成纤维细胞生长因子-聚乳酸-羟基乙酸共聚物微球。 方法：应用单因素设计，初选匀化方式(超声或旋涡)、超声时间(第1次+第2次：5 s+5 s，5 s+10 s，10 s+5 s，10 s+10 s)、内水相体积(50，100，200，250，300 μL)、分散介质聚乙烯醇质量浓度(10，20，30，50，70 g/L)、外水相中无机盐浓度(0，250，500，1 000 g/L)、搅拌时间(3，4，5，6，8 h)等缓释微球制备基本工艺条件。 主要观察指标：各制备工艺条件下微球粒径、载药量和包封率。 结果：单因素试验结果表明，制备碱性成纤维细胞生长因子微球时，超声时间和搅拌时间对于包封率没有影响；匀化方式应选择2次超声，每次5 s；聚乙烯醇质量浓度在30~70 g/L内较好；内水相体积可固定在50~100 μL；外水相中无机盐的浓度越高越好，还可进一步筛选出最佳浓度。经过初步优化后，其平均粒径为6.68 μm，径距为（1.86±0.22）μm，载药量为(37.00±0.89)×10-3％，包封率为（61.31±1.31）％。 结论：应用单因素试验可以初步优选碱性成纤维细胞生长因子缓释微球制备工艺条件。     

包载雷帕霉素聚乳酸-聚乙醇酸纳米粒子的制备、表征及体外释放试验**☆

背景：新型可生物降解多聚物纳米控释载药制剂能显著改善药物穿透组织能力、再分布时程和滞留时间，可能克服载药基质对血管修复的负性影响，有望避免药物洗脱支架晚期支架内血栓。 目的：制备雷帕霉素-聚乳酸-聚乙醇酸纳米粒子（rapamycin poly(lactic-co-glycolic) acid nanoparticles, RPM-PLGA-NPs）并观察其表征及体外控释性能。 设计、时间及地点：单一样本实验于2003-03/09在中国医学科学院,中国协和医科大学,生物医学工程研究所生物医学材料重点实验室完成。 材料：聚乳酸-聚乙烯醇酸共聚物50∶50由美国Birmingham Polymers 公司提供。 方法：以可生物降解高分子材料聚乳酸-聚乙醇酸共聚物作载药基质，超声乳化-溶剂挥发法制备RPM-PLGA-NPs，采用双室扩散池行体外药物释放试验。 主要观察指标：测定平均载药量、平均包封率；激光光散射实验测定纳米粒子的粒径及分布；扫描电镜观察纳米粒子的表面形态；高效液相色谱法计算体外药物释放量、绘制累积释放曲线。 结果：成功制备了平均粒径为246.8 nm的RPM-PLGA-NPs，平均粒径246.8 nm，粒径分布集中在208~294 nm，呈窄分布；包封率大于77%,平均载药量为19.42%。体外释放近似于零级过程，至2周释放75％的药物。 结论：超声乳化-溶剂挥发法制备RPM-PLGA-NPs稳定可靠，包封效率高，载药量控制稳定，粒径小、范围窄，体外释放药物恒定、具有良好的控释效能。     

70001/VIP输尿管支架生物降解材料丙交酯-乙交酯共聚物在体外的降解及临床应用

摘要目的：文章总结近年国内相关文献,了解输尿管支架材料的临床研究和实验研究进展。 方法：由第一作者检索2001-01/2010-12万方数据库(http://www.wanfangdata.com.cn),检索词为“输尿管支架,疗效,并发症,生物降解”。共收集到135篇关于输尿管支架管临床应用及实验研究方面的文献,排除发表时间较早、重复及类似研究,纳入20篇符合标准的文献。结果：在泌尿外科的实践中,输尿管支架管是常用的器械,可以用于尿石症、尿路重建、泌尿系创伤等。它的主要作用是扩张梗阻或狭窄的输尿管将尿液内引流入膀胱,减少肾或输尿管瘘的同时,促进输尿管吻合口的愈合。输尿管支架材料为非生物降解性材料,带管期间患者会出现膀胱刺激症状或发生支架管移位、膀胱输尿管尿液返流和支架管表面结石等并发症。高分子降解性输尿管支架材料体内外生物降解性质的研究处于基础研究阶段。结论：输尿管内支架在泌尿外科中作用显著,但是必需了解及注意预防内支架可能发生的并发症,以便取得更好的疗效。目前各国学者正努力研制更为适宜的输尿管支架材料。关键词：输尿管支架;疗效;并发症;生物降解;生物相容性doi:10.3969/j.issn.1673-8225.2011.12.032     

PLGA-Nogo A抗体缓释微球对大鼠脊髓损伤神经再生的影响

BACKGROUND： Nogo A antigen is the major inhibiting factor blocking regeneration of the injured spinal cord. Neutralizing Nogo A antigens using Nogo A antibodies may help promote neurite regeneration and nervous function recovery. For successful regeneration, sustained release of the antibody from a biodegradable material loaded with Nogo A antibodies to the injury site is required. OBJECTIVE： To compare the therapeutic effects of poly lactic-co-glycolic acid （PLGA）-Nogo A antibody delayed-release microspheres and Nogo A antibody alone on spinal regeneration in Sprague-Dawley rats with complete transverse injury to the spinal cord. DESIGN, TIME AND SETTING： A randomized, controlled animal trial was performed at the Pharmacological Laboratory of West China Center of Medical Sciences, Sichuan University, between October 2007 and January 2008. MATERIALS： Goat anti-rat Nogo A monoclonal antibody was purchased from Santa, American; goat anti-rat neurofilament 200 monoclonal antibody was from Zhongshan Goldenbridge, Beijing, China; PLGA-Nogo A antibody delayed-release microspheres were provided by the College of Pharmacy, Sichuan University. METHODS： A total of 36 adult female Sprague Dawley rats were used to establish models of completely transected spinal cord injury, at T10. Animals were randomly divided into three groups （n=12）： model, Nogo A antibody alone, and Nogo A antibody delayed-release microsphere groups. After transverse injury of the spinal cord, 50 μ L normal saline solution, 50 μL normal saline solution containing 50μL g Nogo A antibody, and 50 μL normal saline solution containing 50 μg Nogo A antibody microspheres were administered to the respective groups at the injury site. MAIN OUTCOME MEASURES： The expression of Nogo A and neurofilament 200 in injured spinal cord was tested immunohistochemically, and motor function of rats was assessed by Basso-Beattie-Bresnahan （BBB） locomotor rating scale. RESULTS： Four weeks after injury, expression of Nogo A in microsphere group was significantly less than model and Nogo A antibody alone groups （P 〈 0.05）; while there was no significant difference between model and Nogo A antibody alone groups （P 〉 0.05）. Ten weeks after injury, microsphere group showed a significantly greater expression of neurofilament 200 than model and Nogo A antibody alone groups （P 〈 0.05）; while no significant difference was found between model and Nogo A antibody alone groups （P 〉 0.05）. At postoperative weeks 5 and 6, the score of BBB locomotor rating scale in microsphere group was significantly greater than the model group （P 〈 0.05）, and at postoperative weeks 7 10, the score was much greater than model and Nogo A antibody alone groups （P 〈 0.05）. CONCLUSION： Nogo A antibody delayed-release microspheres decreased Nogo A expression, increased neurofilament 200 expression in the injured spinal cord of rats, and promoted recovery of motor function through sustained drug release over a long-term period.     

重组人骨形态发生蛋白2缓释微球的制备与评价*☆

目的：针对重组人骨形态发生蛋白2(recombinant human bone morphogenetic protein-2,rhBMP-2)在体内半衰期短、易被稀释代谢的问题，探讨利用聚乳酸-羟基乙酸共聚物(PLGA)制备载rhBMP-2微球的可行性和制备工艺，并观察其载药、释药特性。 方法：①采用W/O/W型复乳化-溶剂挥发技术制备rhBMP-2/PLGA缓释微球，并对微球的粒径和形态、包封率和载药量，体外释放性质进行测定。②异位成骨实验：昆明小鼠12只，在右侧大腿股内侧肌袋内植入含rhBMP-2的50 mg PLGA微球，4周后取材，观察成骨情况以初步检测微球中的蛋白质活性。 结果：①rhBMP-2/PLGA缓释微球形态良好，粒径主要集中在50~60 μm，包封率为（37.52±4.31）%，载药率为（5.12±1.32）%。②微球的释放存在突释，7 d内释放的药物量超过40%，大约90%的药物量于42 d内释放完全。③载药微球植入鼠股部肌袋4周，材料周围有明显的骨形成。 结论:制备的rhBMP-2/PLGA微球可以缓慢释放有活性的rhBMP-2，具有临床应用的可行性。     

BCNU-PLGA缓释可降解微球的制备与特征

目的选择不同分子量及成份的聚乳酸/羟基乙酸(PLGA)共聚物材料,考察粒径、表面形态、包封率、二氯甲烷残留量及体外释放的特点。方法以溶剂挥发法制备卡氮芥-聚乳酸/羟基乙酸(BCNU-PLGA)缓释微球,以扫描电子显微镜观察微球表面形态、测定微球直径,以高效液相色谱法测定微球包封率和体外药物释放,气相色谱法进行二氯甲烷残留量分析。结果BCNU-PLGA缓释微球粒径随分子量升高而增大,表面呈球形,包封率达90%,二氯甲烷残留量6．85‰,体外释放时间达3周。结论溶剂挥发法制备的BCNU-PLGA缓释微球释药可达3周以上,并维持较高药物浓度,为颅内缓释化疗提供新的方法。     

Two-dimensional gel electrophoresis of peripheral nerve proteins: Optimized sample preparation

For proteomic analysis, sample preparation plays a crucial role in two-dimensional gel electrophoresis (2DE), since, very often, each tissue or cell culture requires specific treatments. In the present paper, we report a sample preparation procedure suitable for 2DE that was done on peripheral nerve using bovine sciatic nerves and human sural nerve biopsies. We obtained an appreciable reduction of tissue heterogeneity using protein extracts obtained from nerve-fiber bundles instead of the entire nerve. In addition, we optimized 2DE protein separation using a combination of CHAPS, Triton X-100, and SB3-10 detergents in an isoelectric-focusing (IEF) buffer. The reported experimental procedures appear to be essential for 2DE separation of peripheral nerve proteins for the establishment of a reference map.     

The multiple dimensions of sustained attention

Sustained counting (or temporal numerosity judgements) has been one of the key means of investigating anterior attentional processes. Forty-three patients with localised lesions to the frontal lobes were assessed on two tests of the ability to count the number (8-22) of stimuli presented at either a slow (roughly one per 3 sec) or fast (roughly three per sec) rate. Patients with lesions to the Superior Medial (SM) region (particularly Brodmann areas 24, 32, and 9) were impaired both in the Slow condition and also in the Fast condition, where they underestimated the number of stimuli. Patients with Right Lateral (RL) lesions (8, 45, and 46) also had difficulties in the Fast condition, especially when the number of targets was greater than 15. The results are considered from the perspectives of alternative positions on anterior attentional processes developed by Posner and Petersen (1990) and by Stuss et al. (1995). The most plausible interpretation is in terms of energising processes which involve the SM frontal cortex and monitoring processes which involve the RL frontal cortex.     

Fatigue induces greater brain signal reduction during sustained than preparation phase of maximal voluntary contraction

Animal studies have shown that there are cell populations only discharging phasically before a motor task and others only active tonically during holding phase of the task. How muscle fatigue influences these two types of cell populations, however, is unknown. Because the phasic neurons are only active briefly before the task but the tonic ones are active continuously throughout the task, we hypothesized that fatigue would have a less effect on cortical signals during the preparation phase (representing phasic discharge) than that during the sustained phase (representing tonic discharge). Eight participants performed 200 handgrip maximal voluntary contractions (MVCs) with simultaneous recordings of scalp electroencephalographic (EEG), handgrip force, and finger flexor surface electromyographic (EMG) signals. Power spectrograms of the EEG during the preparation and sustained phases were analyzed in each of the five 40-trial blocks, with data from the first block representing a condition of moderate fatigue and the last, severe fatigue. Movement-related cortical potential (MRCP) was derived by trigger-averaging 40 EEG epochs in each block. The power of all EEG frequencies did not alter significantly during the preparation phase but decreased significantly during the sustained phase of the contraction. The MRCP negative potential (NP) related to motor task preparation only showed minimal changes. These results suggest that MVC-induced fatigue has differential effects on cortical signals during motor task preparation compared to its execution and maintenance. The signals of the two phases may represent activities of the two cortical cell populations previously found by animal studies.     

Neuroendocrine correlates of sustained stress: The activity-stress paradigm

Rats sacrificed after 4 days in the activity-stress paradigm or after 4 days of food restriction had significantly elevated levels of plasma corticosterone as compared to control rats. The approximately 5 fold increase in corticosterone in the stressed treatment groups was consistently found in all experiments. ACTH levels were elevated in activity-stress and food-restricted groups in some experiments but these increases were not statistically significant. Prolactin levels were significantly elevated in food-restricted group rats as compared to controls or activity-stress group animals in one experiment but this finding was not repeated in further experiments. In a second series of experiments, rats from activity-stressed and food-restricted treatment groups and controls were exposed to an acute stressor for 15 min prior to sacrifice to assess the effects of prior sustained stress on hormonal responses to an acute stressor. Exposure to 15 min of immobilization or intermittent footshock immediately prior to sacrifice increased plasma levels of corticosterone, ACTH and prolactin in control, food-restricted and activity-stressed rats. Generally, hormonal responses to the acute stress were similar in all treatment groups. However, in two experiments where the resting levels of corticosterone were especially elevated in the activity-stress group, the acute stress-induced rise in corticosterone was less than that seen for the other two treatment groups. In another experiment, administration of dexamethasone suppressed acute stress-evoked levels of ACTH and corticosterone in control, activity-stressed and food-restricted rats. Thus, rats exposed to 4 days of sustained stress were found to have consistently elevated resting levels of corticosterone.(ABSTRACT TRUNCATED AT 250 WORDS)     

The stability of sustained oscillations in symmetric cooperative-competitive networks

Cohen and Grossberg (1983) proved that a large class of neural networks can function as stable content addressable memories. These Cohen-Grossberg networks were designed to include additive neural networks as studied by Hopfield (1984), and shunting neural networks. The shunting networks included cooperative-competitive networks, also called on-center off-surround feedback networks. The coefficients of the negative feedback signals between populations were drawn from a symmetric matrix. The positive feedback signals were self-excitatory only; that is, no node took excitation from any of its neighbors. The question was next raised concerning how much the Cohen-Grossberg form for a content addressable memory could be generalized. Cohen (1988) showed that if the excitatory on-center was broadened to admit positive feedback from neighboring populations, then persistent oscillations were possible. In this work, the stability of some of these oscillations is shown by studying the Hopf bifurcation constructed in Cohen (1988). These neural networks are transformed to a standard coordinate system and the computation of a coefficient which determines the stability of the oscillations near the Hopf bifurcation is carried out. The negativity of this coefficient implies the bifurcating periodic orbits are stable.     

The functional anatomy of gaze-evoked tinnitus and sustained lateral gaze

OBJECTIVE: To identify neural sites associated with gaze-evoked tinnitus (GET), an unusual condition that may follow cerebellar-pontine angle surgery. METHODS: The authors examined eight patients with GET and used PET to map the neural sites activated by lateral gaze in them and seven age- and sex-matched control subjects. RESULTS: In patients with GET, tinnitus loudness and pitch increased with lateral gaze and, to a lesser extent, up and down gaze. Evidence for neural activity related to GET was seen in the auditory lateral pontine tegmentum or auditory cortex. GET-associated nystagmus appears to activate the cuneus and cerebellar vermis. These sites were found in addition to an extensive network that included frontal eye fields and other sites in frontal, parietal, and temporal cortex that were activated by lateral gaze in seven control subjects and the patients. The unilateral deafness in patients with GET was associated with expansion of auditory cortical areas responsive to tones delivered to the good ear. In addition to GET, unilateral deafness, end-gaze nystagmus, and facial nerve dysfunction were common. CONCLUSIONS: Patients with GET have plastic changes in multiple neural systems that allow neural activity associated with eye movement, including those associated with the neural integrator, to stimulate the auditory system. Anomalous auditory activation is enhanced by the failure of cross-modal inhibition to suppress auditory cortical activity. The time course for the development of GET suggests that it may be due to multiple mechanisms.