依托泊苷长循环热敏前体脂质体的制备工艺研究

目的:对依托泊苷(Etoposide,VP-16)长循环热敏前体脂质体的制备工艺进行研究,并对该制备工艺进行方法学及制剂质量考察。方法:应用薄膜分散法制成VP-16长循环热敏脂质体,进一步借助冷冻干燥技术进行依托泊苷长循环热敏前体脂质体的制备;采用zeta电势测定仪及HPLC等技术进行方法学考察,主要包括脂质体的包封率、粒径、载药量、电位、释放度、稳定性。结果:VP-16长循环热敏前体脂质体水合形成长循环热敏脂质体,粒径为(105.2±3.4)nm,Zeta电位为(-11.9±1.7)m V,包封率可达96.8%;该脂质体在相变温度42℃下药物释放达到96%以上。结论:VP-16长循环热敏前体脂质体的制备工艺稳定,脂质体载药量大,包封率高;药物含量及包封率的测定方法简单、快速而准确,因而,该研究可为VP-16开发成静脉注射用新制剂提供数据支持。     

紫杉醇长循环热敏前体脂质体的制备与表征

目的:研究紫杉醇长循环热敏前体脂质体的制备并对其性质进行考察.方法:采用薄膜分散法制备紫杉醇长循环热敏脂质体,再用冷冻干燥技术制备紫杉醇长循环热敏前体脂质体;采用激光粒度仪考察粒径和Zeta电位;采用高效液相色谱法研究其含量与包封率;并考察脂质体的体外释药特性.结果:紫杉醇长循环热敏前体脂质体水合后形成紫杉醇长循环热敏脂质体,粒径均值为(108.6 ±3.6)nm,Zeta电位的均值为(-12.2±1.8)mV,包封率可达96.2％;该脂质体在相变温度42℃下药物释放达到95％以上.结论:紫杉醇长循环热敏前体脂质体的制备工艺稳定,载药量大,包封率高,具有良好的热敏性;含量及其包封率测定方法简单、快速、准确.本实验可为紫杉醇静脉注射用新制剂的开发提供研究基础.     

全反式维甲酸前体脂质体的制备及体外评价

目的:制备维甲酸前体脂质体,并对其体外性质进行考察。方法:采用乙醇注入结合冷冻干燥法制备前体脂质体;微柱离心-高效液相色谱法测定脂质体的包封率;并进一步对其粒径、Zeta电位、血浆释放率及乙醇残留量进行测定。结果:所制备的前体脂质体包封率为95.2%,Zeta电位为-(28.4±17.5)mV,粒径为(170±29)nm,乙醇残留量为3.98%。结论:乙醇注入结合冷冻干燥法制备的维甲酸前体脂质体包封率高,粒径均匀,稳定性好。     

鬼臼毒素衍生物脂质体处方和制备工艺优选

目的:优选鬼臼毒素衍生物5-氟尿嘧啶乙酸鬼臼酯(5-FPE)脂质体处方和制备工艺。方法:采用薄膜超声分散法制备5-FPE脂质体,以包封率为指标通过正交试验法优选制备处方和工艺,并考察制备的脂质体的包封率、载药量、形态、粒径分布、Zeta电位及在25、4℃条件下存放10d后的体外稳定性。结果:确定了最优处方和工艺,以此制备的3批脂质体的平均包封率为66.45%,平均载药量为7.97%,粒径均值为284.7nm,平均Zeta电位为—22.15mV;脂质体存放10d后包封率下降,但在4℃条件下存放的脂质体的包封率变化比25℃的更小。结论:以优选处方和工艺制备5-FPE脂质体具有可行性,可为进一步的制剂研究提供基础。     

唑来膦酸阳离子脂质体的制备及其体外特性表征

目的制备唑来膦酸阳离子脂质体,并对其体外特性进行表征。方法采用薄膜分散法制备唑来膦酸阳离子脂质体,以包封率、载药量、平均粒径、Zeta电位为评价指标,对处方及工艺进行单因素考察,并对其体外特性进行表征。结果确定处方工艺为DPPC与DC-Chol比例为3∶1,PBS水化体积10 m L,旋转蒸发时间60 min,超声均化5 min,制备得到的阳离子脂质体的平均粒径、聚分散指数、包封率、载药量和Zeta电位分别为(106.76±1.94)nm,0.262±0.027,(38.54±0.99)%,(3.42±0.27)%,+(42.37±2.60)m V,唑来膦酸阳离子脂质体体外释药具有缓释靶向特性,药物释放曲线符合Weibull方程模型。结论采用薄膜分散法制备的唑来膦酸阳离子脂质体具有较高的稳定性,为其药动学和药效学研究奠定了基础。     

洛伐他汀自组装前体脂质体的制备及其理化性质的研究

目的:为研究洛伐他汀新剂型,制备洛伐他汀新型前体脂质体,并对其质量进行考察。方法:采用一种新型前体脂质体制备方法将洛伐他汀制成自组装前体脂质体,对水合后脂质体的形态、粒径、Zeta电位、包封率、自组装速度、稳定性等进行考察,验证这种新型前体脂质体制备方法用于制备洛伐他汀脂质体的可行性。结果:所形成的洛伐他汀脂质体包封率为95.4%±6.7%,平均粒径为(327.4±29.6)nm,Zeta电位值为-(22.4±1.5)mV。洛伐他汀自组装前体脂质体可在60 s内自发形成脂质体并达到分散平衡;以人工胃液为稀释介质,洛伐他汀脂质体在12 h内稳定。结论:采用新型前体脂质体制备方法可将洛伐他汀制成洛伐他汀脂质体,形成的脂质体包封率较高且具有良好的稳定性。     

猪苓多糖长循环脂质体的制备及其质量控制

目的：研究猪苓多糖长循环脂质体的制备方法，并对其质量进行控制。方法：逆相蒸发法制备猪苓多糖长循环脂质体，采用紫外分光光度法测定脂质体中猪苓多糖的包封率和载药量，透射电镜观察形态，激光散射法测定粒径大小，离心加速实验考查稳定性。结果：猪苓多糖长循环脂质体平均粒径为67．8nm，药物平均包封率为93．10％，平均载药量为13．68％。脂质体外观圆整而均匀，渗漏率小，稳定性好。结论：用逆相蒸发法可制备包封率高、稳定性好的猪苓多糖长循环脂质体。质量控制方法简单，快速准确，重复性好。     

环孢素A脂质体制备及其体外释药方法学考察

目的：考察环孢素A（cyclosporinA,csA）脂质体的制备方法、理化性质及其体外释放行为。方法：比较薄膜分散法、逆向蒸发法、乙醇注入法、乙醚注入法所得的环孢素A脂质体（CsA—Lip）,并以包封率和载药量为综合指标,正交设计优化CsA—Lip处方工艺;分别采用动态透析法和超速离心法研究CsA—Lip的体外释放行为。结果：乙醇注入法制备CsA—Lip的平均粒径为（80．41±3．12）nm,包封率为（87．09±0．03）％,载药量为（4．98±0.45）％,24h释放44％。结论：经优化制备的CsA脂质体具有较高的包封率和载药量,并具有缓释作用。     

多肽GRGDS修饰的紫杉醇长循环靶向脂质体的体外评价

目的:本研究以甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸(glycine-arginine-glycine-aspartic acid-serine,GRGDS)五肽修饰的脂质体作为抗癌药物.紫杉醇的载体,对其体外理化性质和细胞毒作用进行评览价.方法:采用化学偶联合成DSPE-PEG-GRGDS,以此作为导向性材料,采用薄膜分散法制备载紫杉醇的PEG修饰长循环脂质体(GRGDS-SSL-PTX),并对脂质体的包封率、粒径和体外释放率等性质进行了考察,同时采用人卵巢癌SKOV-3细胞和人乳腺癌MCF-7细胞进行了体外细胞生长抑制的评价.结果:与普通紫杉醇长循环脂质体(SSL-PTX)相比,本研究制备的紫杉醇主动靶向脂质体(GRGDS-SSL-PTX)的粒径、包封率、载药量、体外释放及稳定性等理化性质无显著差异,包封率约为95%,平均粒径为(115.5±2.2)和(117.5±1.3)nm.冰冻蚀刻透射电镜观察结果表明,脂质体外观基本圆整且均匀分散.体外释放结果表明,12 h内分别有67.9%和72.3%的PTX从SSL-PTX和GRGDS-SSL-PTX中释放.体外细胞毒实验结果表明,GRGDS-SSL-PTX对人卵巢癌SKOV-3细胞和人乳腺癌MCF-7细胞的生长抑制作用均有增强,分别为SSL-PTX的1.42倍和2.12倍.结论:GRGDS五肽修饰的紫杉醇靶向脂质体成功制备,将有利于体内肿瘤的靶向治疗效果.     

甘草次酸介导pH敏感主动靶向长循环阿霉素脂质体的制备及其药物动力学

目的制备甘草次酸(glycyrrhetinic acid,GA)介导的pH敏感主动靶向长循环阿霉素(doxorubicin,DOX)脂质体(liposomes,LP)(GA-PEG2000-N=CH-DOXLP)并测定其在大鼠体内药物动力学参数。方法采用薄膜分散法制备甘草次酸介导pH敏感主动靶向长循环阿霉素脂质;采用阳离子交换树脂-微柱离心法测定脂质体的包封率和载药量;动态激光散射法测定脂质体的粒径、粒径分布和Zeta电位;透射电镜观察脂质体形态;透析法测定脂质体在不同pH条件下的体外释放;荧光分光光度法测定阿霉素血浆药物浓度,得到药-时曲线并计算药物动力学参数。结果甘草次酸介导的脂质体(GA-PEG2000-N=CH-DOXLP)和普通脂质体(DOXLP)的粒径分别为(135.5±2.6)nm和(105.6±4.0)nm;包封率分别为(53.8±5.8)%和(52.9±3.5)%,载药量质量分数分别为(2.35±0.16)%和(2.39±0.26)%;Zeta电位分别为-(5.19±0.73)mV和-(1.53±0.57)mV;GAPEG2000-N=CH-DOXLP的AUC(0-72)分别是DOXLP的2.33倍和DOX溶液的5.62倍。结论所制备的甘草次酸修饰的pH敏感主动靶向长循环脂质体制剂学性质稳定并能显著延长其在大鼠体内的循环时间。     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Alzheimer’s disease – current trends in basic and clinical research. Highlights from the 16th ECNP

Advances in the molecular biological knowledge of neuronal nicotinic acetylcholine receptors (nAChRs) have led to a growing interest by the pharmaceutical industry in the development of novel compounds that selectively modulate nAChR function. The ability of (-)-nicotine, an activator of nAChRs, to enhance attentional aspects of cognition in animals and humans, to exert neuroprotective and anxiolytic-like effects, and presumably to mediate the negative correlation between smoking and Alzheimer's (and Parkinson's) Disease, has focused interest on the potential therapeutic utility of modulators of nAChR function for treatment of some of the deficits associated with these progressive, neurodegenerative conditions. Numerous compounds are known which activate nAChRs and which might serve as lead compounds toward the development of such agents. The pharmacologic diversity of neuronal nAChR subtypes suggests the possibility of developing selective compounds which would have more favourable side-effect profiles than existing agents. This broader class of agents, collectively called cholinergic channel modulators (ChCMs), is anticipated to encompass compounds which would have more favourable side-effect profiles than existing agents, which generally exhibit low selectivity. This selectivity may be achieved by preferentially activating some subtypes of nAChRs (i.e., Cholinergic Channel Activators, ChCAs) or inhibiting the function of other subtypes (Cholinergic Channel Inhibitors, ChCIs). An overview of the biology of nAChRs and the rationale for the use of ChCMs for the treatment of dementia related to neurodegenerative diseases are presented, followed by a discussion of lead compounds and compounds under consideration for clinical evaluation.     

Steroidal sapogenin contents in some domestic plants

In order to find out the values of the steroid resources for the future use. the compositions and contents of steroidal sapogenins from 13 domestic plants have been investigated. As a result,Dioscorea nipponica, D. quinqueloba andSmilax china were found to have large amount of diosgenin. And pennogenin inTrillium kamtschaticum andParis verticillata, yuccagenin inAllium fistulosum, hecogenin inAgave americana and neochlorogenin inSolanum nigum were appeared to be major steroidal sapogenins.