肝脏体外模型及其在毒理学方面的应用

肝脏体外模型发展很快并日趋成熟。目前 ,常用的肝脏体外模型包括原代肝细胞模型、离体肝脏模型、肝脏切片模型、肝细胞系模型、亚细胞模型及基因工程细胞模型等 ,其中原代肝细胞模型最为常用。上述模型除了可以应用于药物肝脏毒性机制的研究之外 ,还可以用于药物毒性的高通量筛选。在今后的研究中 ,如何改善肝脏体外模型的培养条件及完善药物肝脏毒性研究体系是急需解决的课题。     

肝脏“代谢-转运互作”及其对药物药代动力学、疗效和毒性影响的研究进展

肝脏是药物代谢和排泄的主要器官。肝脏药物代谢酶和膜转运体对肝细胞内药物处置及其临床疗效和毒性产生重要影响。近年来,国内外学者发现被称为"代谢-转运互作"的动力学现象,其对药物药代动力学(生物利用度)、药物相互作用具有显著影响。药物代谢酶与转运体间的功能相互作用是目前药物代谢和药代动力学研究的热点之一。本文对肝脏代谢-转运互作进行了探究,并系统阐述了这种互作对药物(特别是Ⅱ相药物代谢)的药物相互作用、药代动力学、临床疗效和毒性反应的影响。今后应进一步阐明肝脏代谢-转运互作机制,有助于研究体内药物处置及药物相互作用,为临床合理用药提供新思路和新技术。     

体外肝细胞模型在毒理学中的应用

尽管整体动物在毒性评价时 ,是不可缺少的 ,但由于动物种类之间存在着种族差异 ,即动物与人之间存在着差异 ,使一些研究结果难以准确地推导到人。除此外 ,从伦理学和减低毒性研究的成本角度出发 ,也应尽量减少动物的使用。近些年来 ,越来越重视体外实验方法及其对体内过程的推导。目前 ,肝细胞体外模型的使用非常广泛 ,特别是离体肝细胞模型更为突出 ,从外源性化合物的毒性筛选、危险性评价到肝损伤机制的研究都广泛地应用到离体肝细胞模型。肝脏含有多种类型细胞 ,如肝细胞、孔状内皮细胞、枯否氏细胞、卫星贮备细胞及脂细胞。这些肝细胞占…     

Caco-2细胞模型在口服药物吸收研究中的应用

目的对Caco 2细胞模型在口服药物肠吸收研究中的应用作一综述。方法在引用了自1974~2004年的32篇文献的基础上,通过介绍并比较体外Caco 2模型和体内药物吸收转运的不同途径,讨论Caco 2单层细胞模型在预测不同类药物体内吸收中的作用。结果Caco 2细胞模型可以预测不同转运途径的药物体内吸收,尤其适用于被动转运药物,这一细胞模型在药物吸收机制、处方组成透膜性和黏膜毒性、药物吸收过程中的相互作用、药物的化学结构和体内转运关系、药物吸收限速因素、药物代谢稳定性及pH对药物吸收的影响等研究中均有较广泛的应用。结论Caco2细胞模型用于预测各种途径的药物吸收,在细胞水平上提供了大量与吸收相关的信息,是口服药物高通量筛选的良好工具。     

肝脏灌流实验技术

<正> 肝脏灌流技术在现代药理学研究中已广泛应用。利用灌流方法可以提供在体和离体肝脏所必需的营养成分和生理环境。与肝组织匀浆、肝组织切片、肝细胞分离,肝细胞膜以及肝细胞酶提取等研究方法相比,肝脏灌流方法的特点是肝脏的组织结构和门脉系统、肝血窦及Disse间隙等参予物质转运的结构均不受影响。该技术可用于药物代谢、代谢动力学、药物毒性、药物相互作用、胆汁排泄和转运等研究。     

应用药物转运体的药代动力学评价

药物转运体在药代动力学方面起到非常重要的作用,它与药物的吸收、分布、排泄、药效发挥、以及药物毒性作用等密切相关。基于转运体的药物间相互作用,还能影响到临床合并治疗药物之间的药代动力学关系。本研究室已经建立了一整套的实用于药代动力学研究和药物间相互作用评价,高效表达人药物转运体蛋白的体外筛选系统,并已将其应用于新药的筛选研究。此方法的特点在于,以表达人药物转运体蛋白的宿主培养细胞为研究对象,在临床前期提供与临床试验相似的研究结果,今后必将成为药物研发领域有用的评价方法。     

藻酸盐水凝胶的研究进展

藻酸盐是一种无毒、无味的天然多糖高分子,具有一定的生物相容性、生物降解性及低致敏性,被广泛应用于生物医学工程领域。藻酸盐水凝胶是用途广泛且适应性强的生物材料,如用作组织工程的细胞传递载体和支撑基质、药物载体以及体外细胞实验的模型。本文综述藻酸盐的化学性质和结构修饰,及其生物反应。     

中药肝毒性及肝脏保护作用的研究方法进展

近年来,中药的肝毒性越来越被人们所了解和重视,中药的肝毒性及肝脏保护作用的研究方法已被广泛建立。与传统的动物体内药代动力学实验相比,精密肝切片法、肝细胞及亚细胞模型体外实验法得以直观地反映出药物对细胞及组织的影响。基因组学,蛋白质组学,代谢组学的方法利用质谱联用技术找出新的生物标记物,阐明肝毒性机制。这一系列的进展为广大的药学工作者对中药肝毒性及肝脏保护作用的研究提供了较大的帮助。     

药物在体透皮吸收模型

近年来,已有越来越多的药物通过皮肤通道的给药系统,特别是控释系统而应用于临床.美国已有4种药物,即东莨菪碱、硝酸甘油、雌二醇和可乐定被认可,还有一些药物尚在审批中.我国对透皮转运系统的研究亦日益重视.要进一步了解体外研究中透皮系统药物和系统面积、赋形剂以及剂量等不同因素对药物疗效产生的影响,并将这些研究结果应用于临床,必须选择和发展适当的在体透皮吸收动力学模型.鉴此,本文综合各类模型的特点及有关研究以供参考.     

药物体外ADME筛选模型

目前已有很多基于细胞水平的体外模型用于研究药物的吸收、分布、代谢、消除和药物毒性，以提高药物开发的成功率。如用于肠吸收研究的CaCo-2细胞模型、用于代谢研究的肝细胞模型及用于透血脑屏障研究的细胞模型。     

Quantitative in vivo and in vitro sex differences in artemisinin metabolism in rat

1. The pharmacokinetics of the antimalarial compound artemisinin were compared in the male and female Sprague-Dawley rat after single dose i.v. (20 mg.kg) or i.p. (50 mg.kg) administration of an emulsion formulation. 2. Plasma clearance of artemisinin was 12.0 (95% confidence interval: 10.4, 13.0) l.h. kg in the male rat and 10.6 (95% CI: 7.5, 15.0) l.h. kg in the female rat suggesting high hepatic extraction in combination with erythrocyte uptake or clearance. Artemisinin half-life was 0.5 h after both routes of administration in both sexes. Values for plasma clearance and half-lives did not statistically differ between the sexes. 3. After i.p. administration artemisinin AUCs were 2-fold higher in the female compared with male rat (p 0.001). Artemisinin disappearance was 3.9-fold greater in microsomes from male compared with female livers and it was inhibited in male microsomes by goat or rabbit serum containing antibodies against CYP2C11 and CYP3A2 but not CYP2B1 or CYP2E1. 4. The unbound fraction of artemisinin in plasma was lower (p 0.001) in plasma obtained from the male (8.8 2.0%) compared with the female rat (11.7 2.2%). 5. The possibility of a marked sex difference, dependent on the route of administration, has to be taken into account in the design and interpretation of toxicological studies of artemisinin in this species.     

Quantitative in vivo and in vitro sex differences in artemisinin metabolism in rat

1. The pharmacokinetics of the antimalarial compound artemisinin were compared in the male and female Sprague-Dawley rat after single dose i.v. (20 mg x kg(-1)) or i.p. (50 mg x kg(-1)) administration of an emulsion formulation. 2. Plasma clearance of artemisinin was 12.0 (95% confidence interval: 10.4, 13.0) 1 x h(-1) x kg(-1) in the male rat and 10.6 (95% CI: 7.5, 15.0) 1 x h(-1) x kg(-1) in the female rat suggesting high hepatic extraction in combination with erythrocyte uptake or clearance. Artemisinin half-life was approximately 0.5 h after both routes of administration in both sexes. Values for plasma clearance and half-lives did not statistically differ between the sexes. 3. After i.p. administration artemisinin AUCs were 2-fold higher in the female compared with male rat (p < 0.001). Artemisinin disappearance was 3.9-fold greater in microsomes from male compared with female livers and it was inhibited in male microsomes by goat or rabbit serum containing antibodies against CYP2C11 and CYP3A2 but not CYP2B1 or CYP2E1. 4. The unbound fraction of artemisinin in plasma was lower (p < 0.001) in plasma obtained from the male (8.8 +/- 2.0%) compared with the female rat (11.7 +/- 2.2%). 5. The possibility of a marked sex difference, dependent on the route of administration, has to be taken into account in the design and interpretation of toxicological studies of artemisinin in this species.     

Interindividual variability in metabolic activation in humans in vivo

In assessing interindividual variability in metabolic activation, the toxic metabolite is often too unstable for conventional analysis. Possible alternatives include a stable product of the reactive metabolite e.g. cysteinyl derivatives of N-acetyl-4-benzoquinoneimine, the toxic metabolite of paracetamol, adducts with DNA or protein, and indirect measurement of the activity of the enzyme(s) producing the active metabolite. An example of the last approach is the use of furafylline, a highly specific inhibitor of human CYP1A2, to determine the extent of the metabolic activation of the cooked food mutagens PhIP and MeIQx. The extent of inhibition, determined from levels of unchanged amine in urine, is an indirect measure of the activity of the activation pathway. Further refinement of this approach, allied to improved measures of the biological process of interest should prove of value in evaluating interindividual variability and its role in the risk assessment process.     

Theophylline kinetics in peripheral tissues in vivo in humans

Several biochemical and cellular effects have been described for methylxanthines under in vitro conditions. However, it is unknown, whether threshold concentrations required to exert these effects are attained in target tissues in vivo. We therefore employed the microdialysis technique for measuring theophylline concentrations in peripheral tissues under in vivo conditions.Following in vitro and in vivo calibration, microdialysis probes were inserted into the medial vastus muscle and into the periumbilical subcutaneous adipose layer of healthy volunteers. Following single oral dose administration of 300 mg or i.v. infusion of 240 mg theophylline, in vivo time courses of theophylline concentrations were monitored in tissues and plasma. Major pharmacokinetic parameters (c_max, t_max, AUC) were calculated for plasma and tissue time courses. The mean AUC_tissue /AUC_plasma-ratio was 0.56 (p.o.) and 0.55 (i.v.) for muscle and 0.55 (p.o.) and 0.72 (i.v.) for subcutaneous adipose tissue.We conclude that microdialysis provides important information on the distribution and the tissue pharmacokinetics of theophylline.Abbreviations FPIA Fluorescence polarisation immuno assay - AUC Area under the curve - t_max Time to peak concentration - c_max Peak concentration     

休克时血中氧自由基的变化

本实验测定10名休克患者血浆和红细胞的丙二醛(MDA)、血浆总抗的氧化活性(AOA)的含量。结果表明:休克病人红细胞膜和血浆 MDA 含量(4.298±0.722;5.348±0.834)与对照组(3.235±0.682;4.356±1.081)比较明显增高(P<0.05);血浆 AOA(39.65±7.858)与对照组(48.21±10.81)比较明显降低(P<0.01)。提示:休克时,患者机体内自由基反应增强是引起组织细胞损伤的原因之一。     

Changes in angiopoietin expression in glomeruli involved in glomerulosclerosis in rats with daunorubicin-induced nephrosis

AIM: To study the potential pathological role of endogenous angiopoietins in daunorubicin-induced progressive glomerulosclerosis in rats. METHODS: Seventy male Wistar rats were allocated randomly into a daunorubicin group (DRB; n=40) or a control group (n=30). The rats in the DRB group were injected with DRB (15 mg/kg), in their tails. Subsequently, at intervals of 1, 2, 4, 6, 8, and 12 weeks, 5 male Wistar rats in each group were chosen randomly for 24 h urinary protein quantitative measurements (24 h UPQM), and determination of plasma tumor necrosis factor alpha (TNF-alpha), angiopoietin-1 (Ang1), and angiopoietin-2 (Ang2) levels. Kidney sections were examined by electron microscopy, Periodic Acid Schiff (PAS) staining, immunohistochemical staining and in situ hybridization histochemistry. RESULTS: As glomerulosclerosis progressed in the DRB group, expression of Ang1 mRNA and protein in glomeruli decreased and expression of TNF-alpha protein, Ang2 mRNA and protein in glomeruli increased. Expression of Ang1 mRNA and protein in glomeruli were negatively correlated with 24 h UPQM, Fn protein expression, and mean area of extracellular matrix (MAECM). In comparison, expression of Ang2 mRNA and protein in glomeruli were positively correlated with 24 h UPQM, Fn protein expression and MAECM; furthermore, there was a positive correlation between plasma Ang2 and 24 h UPQM. Plasma TNF-alpha and expression of TNF-alpha in glomeruli were positively correlated with expression of Ang2 mRNA and protein in glomeruli. There was a negative correlation between Ang1 protein expression and Ang2 protein expression in glomeruli. CONCLUSION: During DRB-induced glomerulosclerosis, podocyte injury led to a shift in the balance of Ang1 and Ang2 in glomeruli. Increased TNF-alpha in plasma and glomeruli may upregulate Ang2 expression in glomeruli. Elevated Ang2 in both plasma and glomeruli may mediate protein permeability through the glomerular filtration barrier. Moreover, local expression of Ang2 may facilitate the progress of glomerulosclerosis by upregulating a component expression of extracellular matrix.     

Trichinellosis in immigrants in Switzerland

We describe a case of trichinellosis diagnosed at the Division of Infectious Diseases, Hospital of Lugano, in January 2009. This case was associated with a cluster of cases and was traced to the consumption of contaminated meat after a wild boar hunt in Bosnia.