多药物耐药基因多态性与缺血性脑卒中患者阿司匹林抵抗的相关性分析

目的:探讨多药物耐药基因多态性与缺血性脑卒中患者阿司匹林抵抗的相关性。方法:选取缺血性脑卒中患者230例,根据其对阿司匹林的敏感程度,将阿司匹林敏感(AS)80例设为对照组,阿司匹林抵抗(AR)150例设为研究组,对两组多药物耐药基因进行检测,分析其与缺血性脑卒中患者阿司匹林抵抗的相关性。结果:研究组吸烟患者概率、空腹血糖水平以及总胆固醇水平高于对照组,差异有统计学意义(P<0.05),研究组性别、年龄、高血压病史、饮酒史、三酰甘油水平、高密度脂蛋白以及低密度脂蛋白水平与对照组比较,差异无统计学意义(P>0.05);研究组等位基因检测数量为158,对照组组等位基因检测数量为446,其中研究组C3435T位点的T等位基因频率及CT+rI-11基因型高于对照组,差异有统计学意义(P<0.05);阿司匹林抵抗独立危险因素包含吸烟史、基因型、空腹血糖、总胆固醇(P<0.05)。结论:C3435T基因多态性与阿斯品抵抗有关,吸烟史、基因型、空腹血糖以及总胆固醇含量是阿司匹林抵抗的独立危险因素。

多药物耐药基因多态性与缺血性脑卒中患者阿司匹林抵抗的相关性

目的 探讨多药物耐药（ABCB1/MDR1）基因多态性与缺血性脑卒中患者阿司匹林抵抗（AR）的关系。方法 纳入2014年9月至2016年5月在青岛大学附属医院神经内科因脑梗死住院的患者300例，根据血栓弹力图（TEG）结果将其分为阿司匹林抵抗（AR）组和阿司匹林敏感（AS）组。采用聚合酶链反应–限制性片段长度多态性技术（PCR–RFLP）和直接测序方法对ABCB1基因C1236T、G2677T/A、C3435T 3位点进行基因多态性检测。结果 C1236T、G2677T/A、C3435T两两间分别存在连锁不平衡（D′＝0.8；r2＝0.9）。位点C3435T T的等位基因频率在AR组和AS组中分别为57.3%和43.1%，差异有统计学意义（χ2＝9.143，P＝0.002），且AR组中（CT＋TT）基因型高于AS组，差异亦有统计学意义（χ2＝4.369，P＝0.037）。而C1236T和G2677T/A等位基因频率及基因型分布在两组间差异均无统计学意义。对3位点所构建的单倍型进行分析，单倍体（C–T–T）的OR值为1.602 （χ2＝5.374，P＝0.02），单倍体（C–G–C）的OR值为0.495（χ2＝8.775，P＝0.003），单倍体（T–G–C）的OR值为3.010 （χ2＝5.846，P＝0.015），单倍体（T–T–T）的OR值为3.308（χ2＝4.650，P＝0.031）。结论 C3435T基因多态性与缺血性卒中患者AR有关。单倍体（C–T–T，T–G–C，T–T–T）亦与缺血性卒中患者AR发生有关。

利用新型载体运转MDR1 siRNA以逆转胰腺癌化疗耐药性的研究

目的:以新型载体运转MDR1 siRNA导入胰腺癌细胞株后,观察其多药物耐药基因(MDR1)的表达及其对胰腺癌化疗耐药性的影响。方法:采用RNA干扰技术,构建可用于包装成自我复制rAAV病毒载体的质粒,以运转不同长度的MDR1 siRNA。采用实时PCR检测MDR1 mRNA的表达,Western印迹法检测总P-糖基化蛋白(P-gp)的表达水平,用流式细胞仪检测细胞表面的P-gp表达,并从不同层面检测胰腺癌细胞株P-gp表达的抑制率,从而筛选出最佳的质粒载体。采用MTT检测IC50值,进行各载体逆转胰腺癌细胞株化疗耐药性的研究。结果:拟用于构建自我复制rAAV病毒载体的25-mer MDR1 siRNA质粒能有效地将目的基因MDR1 siRNA导入胰腺癌细胞株,并予稳定的表达,发挥作用。导入胰腺癌细胞株的MDR1 siRNA能有效地在mRNA水平上沉默MDR1基因,显著抑制其表达,使其蛋白产物P-gp的表达明显减少,及其在细胞膜上的数量显著降低。结果能有效、显著地逆转胰腺癌细胞株的化疗耐药性,转染前SW1990/ADM细胞对ADM的IC50值约是转染后的50倍。结论:采用可用于构建新型sc-rAAV载体的质粒作为投递siRNA的工具,并选择MDR1为研究靶点,通过实验证实该策略在逆转胰腺癌化疗耐药性中的有效性。

难治性癫痫多药耐药机制的研究进展

多药物抵抗是药物治疗难治性癫痫的主要障碍。有研究表明，多药物转运子P糖蛋白的表达增加和活性增强，阻止抗癫痼药物进入大脑是多药物抵抗的主要机制。另外有研究发现P糖蛋白的表达和活性与谷氨酸盐／NMDA受体/COX-2信号途径有关，这可能成为新的解决癫痫多药物抵抗的靶点。

Structure-activity Relationship of Phenothiazines for Inhibition of Protein Kinase C and Reversal of Multidrug Resistance

Studies on structure-activity relationship of phenothiazines (PTZs) forinhibition of protein kinase C (PKC) and reversal of multidrug resistance (MDR) has been made invitro. The results showed that the order of potency of reversal effect of PTZs on MDR is as follows:2-COC_3 H_7 > 2-CF_3 > 2-COCH_3 > H. The type of piperazinyl substitution also significantlyaffected potency against MDR. The results show the order: CH_3 > COOC_2 H_5 > C_2 H_4 OH. Inaddition, PKC plays a marked role in diverse cellular process including MDR. Some derivatives of PTZwas tested for inhibition of PKC, of which PTZ11 showed the highest inhibitory effect of MDR andPKC, implying a potential reversal agent of MDR for tumor therapy in the future. We also tried toexplore the possible binding model of PTZs to PKC. Our molecular-modeling study preliminarilysuggests how these PTZs bind to PKC and provides a structural basis for the design of high affinityPKC-modulator. The infor-mation may be used in the rational design of more effective drugs.

Molecular Cloning of PhoR Sensor Domain from Mycobacterium tuberculosis for Structure-Based Discovery of Novel Anti-Tubercular

The emergence of multidrug-resistant strains （MDR-TB） and extensively drug-resistant strains （XDR-TB） has fuelled the quest for novel drugs and drug targets for its successful treatment. One of the potential candidates as novel TB drug target is the PhoR sensor domain, an extracellular domain of PhoR histidine kinase. PhoR sensor domain is part of the two-component system PhoR-PhoP that senses environmental stimuli and relays the signal to control the expression of 78 virulent associated genes in Mycobacterium tuberculosis. 3D structure of the PhoR sensor domain will facilitate the structure based drug discovery of novel anti- tubercular. In this study, we successfully predicted and isolated the gene encoding PhoR sensor domain from Mycobacterium tuberculosis H37Rv, cloned it in pGEM-T vector and subcloned it in pRSET emGFP expression vector. PhoR sensor domain was successfully cloned and would be used for further expression, purification and crystallization studies.

Hollow iron oxide nanoparticles as multidrug resistant drug delivery and imaging vehicles

Magnetic nanopartides have been used as drug delivery vehicles against a number of cancer cells. Most of these theranostic formulations have used solid iron oxide nanoparticles （SIONPs） loaded with chemotherapeutics as nano-carrier formulation for both magnetic resonance imaging （MRI） and cancer therapy. In this study, we applied the dopamine-plus-human serum albumin （HSA） method to modify hollow iron oxide nanoparticles （HIONPs） and encapsuated doxorubicin （DOX） within the hollow porous structure of the nano-carrier. The new delivery system can load more drug than solid iron oxide nanoparticles of the same core size using the same coating strategy. The HIONPs-DOX formulation also has a pH-dependent drug release behaviour. Compared with free DOX, the HIONPs-DOX were more effectively uptaken by the multidrug resistant OVCAR8- ADR cells and consequently more potent in killing drug resistant cancer cells. MRI phantom and cell studies also showed that the HIONPs-DOX can decrease the T2 MRI signal intensity and can be used as a MR/contrast agent while acting as a drug delivery vehicle. For the first time, the dual application of chemo drug transport and MR imaging using the HIONPs-DOX formulation was achieved against both DOX-sensitive and DOX-resistant cancer cells.

Flexible electrostatic hydrogels from marine organism for nitric oxide-enhanced photodynamic therapy against multidrug-resistant bacterial infection

The abuse of antibiotics in treating microbial infections has led to the emergence and prevalence of drugresistant bacteria.Thus,the development of novel antibacterial materials is attracting increasing attention.Here,a series of flexible electrostatic hydrogels with excellent antibacterial ability were constructed using a mixture of nitric oxide(NO)-releasing nitrated chitosan(CSNO)and mesotetra(4-carboxyphenyl)porphine(TCPP)with salmon sperm DNA(ssDNA)solution.When cultured with gram-negative bacteria under solar simulator irradiation,TCPP-CSNO_(m)ssDNA_(n) hydrogels released reactive oxygen species(ROS)and NO to produce peroxynitrite ions(ONOO^(−)).ONOO−is efficient at killing bacteria,thereby improving the antimicrobial ability of photodynamic therapy against gram-negative bacteria.The hydrogels exhibited powerful antibacterial activity in vivo when used to treat skin infections caused by drugresistant bacteria,making them a promising candidate for clinical applications.A string of antibacterial hydrogels that release ROS and NO synergistically can bring new possibilities for effectively killing drug-resistant bacteria and be of great value in anti-infection wound dressings and other applications.

Discovery of ferrocene-carborane derivatives as novel chemical antimicrobial agents against multidrug-resistant bacteria

Antimicrobial resistance has now become a very serious global public health problem. New drug discovery and development are urgently needed to combat the growing threat of multidrug-resistant (MDR) bacteria. The aim of this study was to explore the potential application of three ferrocene-carborane derivatives as new promising agents to confront the problem of increasing antibiotic resistance. The results of agar diffusion bioassay, minimal inhibitory concentrations (MIC) testing and time-kill assay illustrate their broad-spectrum antimicrobial activities to both American Type Culture Collection (ATCC) control strains and MDR clinical isolates. It is evident that the relevant antimicrobial properties are all in a dose-dependent manner and gradually transform into a bactericidal effect from a bacteriostatic effect with the increasing of the drug concentration. Furthermore, these ferrocene-carborane derivatives have no/little toxic effect on normal cells like HELF cells and lead to little hemolysis at their MICs. This raises the possibility to develop novel antimicrobial drugs using these new ferrocene carborane derivants.

Spectroscopic and electrochemical studies on molecular recognition of tetrathiafulvalene derivative with P-glycoprotein and drug-resistant leukemia cells

Cancer is still one of the important diseases that threatens the health of people. Multidrug resistance(MDR) is the main factor that leads to the failure of cancer chemotherapy. Thus, MDR diagnosis could facilitate the monitoring of the therapy process and realization of efficient treatment of tumors. In this study, we have tried to use a new tetrathiafulvalene(TTF) derivative(TTF-(COONBu4)2) to sensitively recognize the MDR through the multi-signal responsive strategy. The relevant electrochemical and spectroscopic studies demonstrate the specific binding behavior of TTF-(COONBu4)2 with P-glycoprotein(P-gp) as well as drug-resistant leukemia cells. Especially due to the over-expression of specific components of P-gp on the plasma membranes of drug resistant cells, the electrochemical and hydrophilic/hydrophobic features of drug resistant-leukemia cells are apparently different from those of other kinds of leukemia cells. Meanwhile, Fourier transform infrared spectroscopic study illustrates that the most intense vibration band of TTF moieties in the 1400–1600 cm-1 range is almost smeared out upon binding to P-gp, and the binding of TTF-(COONBu4)2 to P-gp may also lead to changes in protein secondary structure and backbone. This observation may advance the development of the new TTF agent for the promising clinical diagnosis and monitoring of MDR of tumors with the aim of successful chemotherapy for human cancer.