Mechanically-induced membrane poration causes axonal beading and localized cytoskeletal damage

Diffuse axonal injury (DAI), a major component of traumatic brain injury, is a manifestation of microstructural cellular trauma and various ensuing neurochemical reactions that leads to secondary neuronal death. DAI is suggested to result from the initial increase in the membrane permeability caused by the mechanical forces acting on the axons. Permeability increases disturb ion balance and lead to cytoskeletal disruption resulting in the impairment of axonal transport. We present an in vitro model that reproduces important features of in vivo DAI such as membrane permeability changes, focal disruption of microtubules, impaired axonal transport, and focal accumulation of organelles. We induced fluid shear stress injury (FSSI) on cultured primary chick forebrain neurons and characterized the resulting structural and morphological changes. In addition, we tested the effect of Poloxamer 188 (P188), a tri-block co-polymer that is known to promote resealing membrane pores. We found that FSSI induces mechanoporation that leads to axonal bead formation, the “hallmark” morphology of DAI. Beads contained accumulated mitochondria and co-localized with focal microtubule disruptions, also a characteristic of DAI. Post-injury P188 treatment prevented FSSI-induced membrane permeability changes and reduced axonal beading to control levels. These results indicate that acute mechanoporation of axons in response to injury is a necessary condition for subsequent axonal pathology, suggesting that membrane integrity is a potential target for therapeutic interventions. P188 provides neuroprotection via resealing the plasma membrane following injury and prevents focal disruption of microtubules and axonal bead formation.     

The effect of old age on liver oxygenation and the hepatic expression of VEGF and VEGFR2

In old age, the liver contains less ATP and hypoxia-responsive genes are upregulated. Age-related changes in hepatic perfusion and the liver sinusoidal endothelial cell (LSEC) could contribute to this altered hepatic oxygen-dependent metabolism by causing intrahepatocytic hypoxia. Furthermore, age-related changes in the LSEC ('pseudocapillarization') have been partially induced by ATP depletion. To investigate whether there is intracellular hypoxia in the old rat liver, pimonidazole immunohistochemistry in intact livers and ATP levels in isolated LSECs were studied from young and old rats. There were no age-related changes. To determine whether defenestration of the LSEC could impair oxygen diffusion, pimonidazole immunohistochemistry was performed in rats treated with poloxamer 407. Despite defenestration, there was no change in pimonidazole staining. Immunohistochemistry was then performed to determine whether there are age-related changes in VEGF and VEGFR2. VEGF staining was not associated with age. However, there was an increase in perisinusoidal VEGFR2 expression with increasing age. In conclusion, liver hypoxia does not occur in old age and LSEC pseudocapillarization does not constitute an oxygen-diffusion barrier. There are no age-related changes in VEGF expression but an increase in perisinusoidal VEGFR2 expression, which has implications for the effects of aging on the hepatic sinusoid.     

奥硝唑温敏性水凝胶的制备及质量控制

目的:制备奥硝唑温敏性水凝胶并建立其质量控制方法。方法:以奥硝唑为主药,泊洛沙姆P407与P188为基质制备凝胶;采用紫外分光光度法测定其中奥硝唑的含量。结果:所制制剂为白色或微黄色的半固体凝胶制剂,检查符合2005年版《中国药典》中的相关规定。奥硝唑检测浓度的线性范围为3.98～43.77mg·L-1(r=0.999 8);平均回收率为98.52%(RSD=1.1%)。结论:本制剂制备工艺简便可行,质量稳定可控。     

膜修复材料在脊髓损伤修复中的研究进展

神经元膜的完整性对其完成特定的生理功能具有重要意义,而脊髓损伤（SCI）会使神经元膜遭到破坏.目前,治疗SCI的一种新思路是在SCI后早期修复受损的细胞膜.就近年来用膜修复材料治疗SCI的进展进行综述,主要包括聚乙二醇（PEG）、泊洛沙姆188（P188）、壳聚糖及一些纳米材料的研究进展;同时指出了目前研究中存在的问题,并对其发展趋势进行了展望.     

Interaction of dispersed cubic phases with blood components

The interaction of aqueous nanoparticle dispersions, e.g. based on monoolein/poloxamer 407, with blood components is an important topic concerning especially the parenteral way of administration. Therefore, the influence of human and porcine plasma on dispersed cubic phases was investigated. Particle size measurements of mixtures with plasma indicated a decrease in particle size. In cryo-transmission electron micrographs, different structures could be found, which arose from the dispersed cubic phases under plasma contact. Non-cubic structures on the particle surface were decomposed first. Several phase transitions with the formation of smaller and sometimes larger particle fractions were observed beside remaining cubic structures. A very low but detectable hemolytic activity was found for the dispersed cubic phases based on monoolein and poloxamer 407, when compared to the hemolytic activity of cubic phases based on monoolein and poloxamer 188, on soy phosphatidylcholine, glycerol dioleate and polysorbate 80 or the parenteral fat emulsion Lipofundin MCT 20%.     

星点设计-效应面法优化芷芎散温敏凝胶的处方及其鼻黏膜渗透特性研究

目的 制备并优化芷芎散鼻用温敏凝胶的处方,并考察其体外释放机制和鼻黏膜渗透特性。方法 利用星点设计-效应面法优化泊洛沙姆温敏凝胶基质处方,然后经Franz扩散池法考察欧前胡素、阿魏酸的体外释放机制及其离体家兔鼻黏膜渗透特性。结果 最优处方为泊洛沙姆407（P407）20%、泊洛沙姆188（P188）6.5%,欧前胡素接近零级释放模型,阿魏酸接近Higuchi模型,处方对欧前胡素和阿魏酸的透过鼻黏膜均具有促进作用。结论 优化所得的处方为芷芎散新给药途径制剂的开发提供基础。     

用Box-Behnken效应面法优化穿心莲内酯纳米乳原位凝胶处方工艺研究

目的:采用Box-Behnken效应面法优化穿心莲内酯纳米乳原位凝胶的处方,为中药经皮给药制剂的研究与开发提供参考。方法:以泊洛沙姆188（P188）和泊洛沙姆407（P407）为凝胶基质,采用凝胶基质的质量分数为考察因素,凝胶温度为考察指标,通过二项式拟合分析得到方程,并建立胶凝温度与2个考察因素之间的数学关系,采用星点设计-效应面法优化穿心莲内酯纳米乳原位凝胶的处方,并对优化处方进行验证。结果:凝胶温度与考察因素存在可信定量关系,且二项式拟合方程置信度高。穿心莲内酯纳米乳原位凝胶的最佳处方为20.00%泊洛沙姆407和5.00%泊洛沙姆188;凝胶温度为（33.8±0.2）℃,处方制备重复性高。结论：该方法适用于穿心莲内酯纳米乳原位凝胶的处方优化,建立的模型预测性良好,优化的制备方法稳定,胶凝温度适宜,可为穿心莲内酯经皮给药制剂的开发提供参考。     

甲硝唑阴道用原位凝胶的处方设计及体外质量评价

目的:研制甲硝唑阴道用原位凝胶,并考察其体外质量.方法:以卡波姆及泊洛沙姆为混合凝胶基质,筛选其最佳配比,制备甲硝唑阴道用原位凝胶.对其体外流变性、黏附性进行考察,并与上市甲硝唑阴道用凝胶做对照,考察其阴道滞留性.结果:原位凝胶的最佳基质配比为泊洛沙姆407的质量分数为17.5%,卡波姆971P的质量分数为1.5%.黏附力测定结果表明其具有较大的温度敏感性.与上市产品相比,原位凝胶可显著增加阴道滞留性.结论:该原位凝胶具有显著的温度敏感性,本品值得进一步研发.     

番茄红素-泊洛沙姆188固体分散体的制备及溶出度和生物利用度研究

目的 ： 采用固体分散体技术,提高番茄红素在水中的溶解度和体外溶出度,从而提高其体内的生物利用度。 方法 ： 以泊洛沙姆188为载体,溶剂法制备番茄红素固体分散体,应用光谱分析和DSC考察其分散特征,溶出度试验测定其体外溶出度,大鼠灌胃后测定其体内生物利用度,用HPLC法测定血药浓度,采用Kinetica软件计算药动学参数。 结果 ： 番茄红素可能以分子复合物状态存在于固体分散体中,且显著提高了番茄红素的溶出度,与市售番茄红素油混悬液为对照,其相对生物利用度为(312.2±96.9)%。 结论 ： 番茄红素-泊洛沙姆188固体分散体制备工艺简单,成本较低,能显著改善难溶性药物番茄红素的生物利用度,具有较好的实际应用价值。     

Novel Tanshinone II A ternary solid dispersion pellets prepared by a single-step technique: In vitro and in vivo evaluation

Novel Tanshinone II A (TA) ternary solid dispersion (tSD) pellets with the combination of polyvinylpyrrolidone and poloxamer 188 as dispersing carriers were prepared by a single-step technique. A formulation screening study showed that the addition of poloxamer 188 to binary TA-PVP system could remarkably promote the dissolution rate of TA from 60% to 100% after 60 min. Scanning electron microscopy study revealed a smooth surface and a tightly packed coating structure. Differential scanning calorimetry analysis confirmed the formation of solid dispersions. In vivo test showed that TA tSD pellets presented significantly larger AUC_0-t, which was 0.76 times more than that of binary solid dispersion (bSD) pellets, 2.87 times more than that of physical mixtures (PMs) and 5.40 times more than that of TA. C_max of TA tSD pellets also increased by 1.82-8.97-fold as that of bSD pellets, PMs and TA. TA tSD pellets generated obviously shortened T_max of (3.80 ± 0.398) h, compared to bSD pellets with (4.15 ± 0.456) h, PMs with (4.65 ± 0.226) h and TA with (5.52 ± 0.738) h. In conclusion, the addition of poloxamer 188 to pellets containing PVP-based solid dispersions could achieve complete dissolution, accelerated absorption rate and superior oral bioavailability. The fluid-bed technique becomes an alternative approach to obtain solid dispersion-coated pellets.