难治性癫痫患儿抗癫痫药物耐受性临床资料分析

难治性癫痫（RE）的发病机制是多年来研究的难点与热点。近年来,研究的重点集中在多药耐药上,认为抗癫痫药物（AEDs）的耐受性是临床上癫痫治疗失败的主要原因之一。进一步的研究表明,脑内多药耐药（MDRl）基因的高表达导致脑实质内药物浓度下降,可能是药物耐受性产生的重要原因。为此,我们在进行癫痫耐药的基础研究同时,总结了我院小儿神经内科1999～2004年诊断的难治性癫痫患儿应用抗癫痫药物治疗的临床资料,并进行分析,旨在为难治性癫痫与耐药的关系提供临床客观依据,并为基础研究及临床合理用药提供线索。     

急性髓系白血病中乳腺癌多药耐药蛋白基因的研究进展

乳腺癌耐药蛋白(BCRP)是新近发现的一种肿瘤耐药相关蛋白,与P-gp和多药耐药相关蛋白(MRP)同属ABC转运蛋白超家族。本文对BCRP的发现、组织表达、结构特点、急性髓系白血病中多药耐药BCRP基因的表达及应用等方面的研究进展进行综述。     

一种新的肿瘤相关耐药蛋白--乳腺癌耐药蛋白

乳腺癌耐药蛋白(BCRP)是1998年才发现的一种与多药耐药(MDR)相关的肿瘤耐药蛋白,它与P-gp和多药耐药相关蛋白(MRP)同属ABC转运蛋白超家族成员.本文就BCRP近两年的研究情况作一综述.     

难治性癫痫患者血清及脑脊液P-糖蛋白检测

目的　探讨难治性癫痫发病机制 ,为寻找难治性癫痫新的治疗方法提供理论依据。方法　采用ELISA方法检测临床确诊为难治性癫痫的 12例患者血清及脑脊液P 蛋白 (P Glu proteis,PGP) ,并与用药物控制良好的 15例癫痫患者和 11例正常人比较 ,用OD值做为参数进行分析。结果　难治性癫痫组血清及脑脊液PGP明显高于癫痫组和正常对照组。结论　PGP可能是促成癫痫耐药的重要因素 ,并可作为癫痫患者耐药的一个客观指标。     

一种新的肿瘤相关耐药蛋白—乳腺癌耐药蛋白

乳腺癌耐药蛋白（BCRP）是1998年才发现的一种与多药耐药（MDR）相关的肿瘤耐药蛋白，它与P-gp和多药耐药相关蛋白（MRP）同属ABC转运蛋白超家族成员。本文就BCRP近两年的研究情况作一综述。     

急性白血病耐药蛋白表达及其检测、逆转技术的进展

1979年Biedler研究中国仓鼠肺细胞时首次发现交叉耐药现象.有多种机制可能与急性白血病（AL）化疗中的多药耐药（MDR）相关.包括肿瘤细胞不能对化疗作用发生程序性死亡或药物不能达到并作用于胞内特定目标.目前血液系统已发现的耐药蛋白主要有P-糖蛋白（P-gp）、多药耐药相关蛋白（multidrug resistance-associated proteins,MRP1）、肺耐药相关蛋白（lung resistance protein,LRP）、乳腺癌耐药蛋白（breast cancer resistance protein,BCRP）,它们同属膜转运蛋白超家族成员,介导AL多药耐药机制.笔者对近年来发现的几种膜转运蛋白超家族成员在AL耐药细胞中的作用机制、表达与预后相关性,逆转剂对耐药蛋白作用效果的评价,基因水平的新型多药耐药逆转技术以及耐药蛋白检测技术的新进展作一综述.     

乳腺癌耐药蛋白及其介导的多药耐药研究进展

最近发现的乳腺癌耐药蛋白(BCRP)是一种不同于P-糖蛋白等的新型多药耐药蛋白,属于ATP结合盒转运子蛋白亚家族成员,为半转运子,以二聚体形式形成活性转运复合体。药敏细胞中转染或过度表达BCRP可导致该细胞耐药,可预示白血病患者的化疗敏感性及预后。     

氯霉素通过线粒体途径诱导白血病多药耐药细胞凋亡

多药耐药（MDR）是影响白血病治疗效果的主要障碍,因耐药机制的复杂性或耐药逆转药物临床应用的不良反应,致使目前尚未解决这一难题.研究发现多药耐药细胞可以阻断半胱天冬酶（caspase）途径介导的细胞凋亡，而线粒体介导途径可以绕过线粒体以上的耐药作用位点，完成凋亡过程。我们初步研究发现，线粒体蛋白合成抑制剂氯霉素具有抑制白血病细胞及白血病多药耐药细胞生长及周期阻滞作用，为此我们探讨了氯霉素诱导白血病多药耐药细胞凋亡的作用及其机制。     

肿瘤细胞对氨甲蝶呤产生耐药生化机制的研究进展

氨甲蝶呤(MTX)作为一种广泛使用的抗肿瘤药物,几十年来人们一直在不断探讨其耐药的具体机制。随着相关检测技术的发展,最近几年对其耐药的理解更加深入,涉及谷氨酰合成酶(分胞浆型cFPGS和线粒体型mFPGS两种异构体)与MTX耐药机制、多药耐药相关蛋白与耐药、二氢叶酸还原酶与耐药间作用的机制。现从药物转运、谷氨酸化以及合成代谢途径认识引起MTX耐药的生化机制,并探讨其在临床的应用前景和意义。     

耐多药和难治性肺结核的原因及防治

目前，结核病的发病率逐渐上升，据WHO估计，全球近有20亿人感染了结核菌。由于种种原因，耐多药（根据国内结核专家在学术会议上讨论对2种或2种以上抗结核药物耐药且包括异烟肼和利福平称为耐多药）和难治性肺结核（将慢性传染源患者、难治的排菌者和重症的肺结核统称为难治性肺结核）近年有所增加，据统计耐多药肺结核和难治性肺结核分别占肺结核的17.1%和3.1%~7.6%，并有大幅度递增趋势。兹将收治的耐多药和难治性肺结核报告如下。1形成原因1.1结核菌耐药性结核菌的耐药性是耐多药和难治性肺结核的主要原因。耐药性分为原发耐药和获得…     

Role of multidrug transporters in pharmacoresistance to antiepileptic drugs

Epilepsy, one of the most common neurologic disorders, is a major public health issue. Despite more than 20 approved antiepileptic drugs (AEDs), about 30% of patients are refractory to treatment. An important characteristic of pharmacoresistant epilepsy is that most patients with refractory epilepsy are resistant to several, if not all, AEDs, even though these drugs act by different mechanisms. This argues against epilepsy-induced alterations in specific drug targets as a major cause of pharmacoresistant epilepsy, but rather points to nonspecific and possibly adaptive mechanisms, such as decreased drug uptake into the brain by intrinsic or acquired over-expression of multidrug transporters in the blood-brain barrier (BBB). There is accumulating evidence demonstrating that multidrug transporters such as P-glycoprotein (PGP) and members of the multidrug resistance-associated protein (MRP) family are over-expressed in capillary endothelial cells and astrocytes in epileptogenic brain tissue surgically resected from patients with medically intractable epilepsy. PGP and MRPs in the BBB are thought to act as an active defense mechanism, restricting the penetration of lipophilic substances into the brain. A large variety of compounds, including many lipophilic drugs, are substrates for either PGP or MRPs or both. It is thus not astonishing that several AEDs, which have been made lipophilic to penetrate into the brain, seem to be substrates for multidrug transporters in the BBB. Over-expression of such transporters in epileptogenic tissue is thus likely to reduce the amount of drug that reaches the epileptic neurons, which would be a likely explanation for pharmacoresistance. PGP and MRPs can be blocked by specific inhibitors, which raises the option to use such inhibitors as adjunctive treatment for medically refractory epilepsy. However, although over-expression of multidrug transporters is a novel and reasonable hypothesis to explain multidrug resistance in epilepsy, further studies are needed to establish this concept. Furthermore, there are certainly other mechanisms of pharmacoresistance that need to be identified.     

Quantitative in vivo microdialysis study on the influence of multidrug transporters on the blood-brain barrier passage of oxcarbazepine: concomitant use of hippocampal monoamines as pharmacodynamic markers for the anticonvulsant activity

Various antiepileptic drugs were shown to be substrates for multidrug transporters at the level of the blood-brain barrier. These ATP-dependent efflux pumps actively limit brain accumulation of xenobiotics and drugs. Intrahippocampal oxcarbazepine perfusion in rat was previously shown to exert anticonvulsant effects associated with increases in extracellular dopamine and serotonin levels. In contrast, preliminary studies in our laboratory revealed that no anticonvulsant or monoaminergic effects could be obtained after systemic oxcarbazepine administration. The present in vivo microdialysis study was conducted to investigate the impact of the transport kinetics of oxcarbazepine across the blood-brain barrier on the observed treatment refractoriness. More precisely, the influence of intrahippocampal perfusion of verapamil, a P-glycoprotein inhibitor, and probenecid, a multidrug resistance protein inhibitor, on the blood-brain barrier passage and anticonvulsant properties of oxcarbazepine were investigated in the focal pilocarpine model for limbic seizures. Simultaneously, the effects on hippocampal monoamines were studied as pharmacodynamic markers for the anticonvulsant activity. Although systemic oxcarbazepine administration alone failed in preventing the animals from developing seizures, coadministration with verapamil or probenecid offered complete protection. Concomitantly, significant increases in extracellular hippocampal dopamine and serotonin levels were observed within our previously defined anticonvulsant monoamine range. The present data indicate that oxcarbazepine is a substrate for multidrug transporters at the blood-brain barrier. Coadministration with multidrug transporter inhibitors significantly potentiates the anticonvulsant activity of oxcarbazepine and offers opportunities for treatment of pharmacoresistant epilepsy.     

A MATE Family Multidrug Efflux Transporter Pumps out Fluoroquinolones in Bacteroides thetaiotaomicron

We cloned a gene, bexA, that codes for a multidrug efflux transporter from the chromosomal DNA of Bacteroides thetaiotaomicron ATCC 29741 by using an Escherichia coli DeltaacrAB DeltaacrEF mutant as a host. Although the initial recombinant construct contained other open reading frames, the presence of bexA alone was sufficient to confer to the E. coli host elevated levels of resistance to norfloxacin, ciprofloxacin, and ethidium bromide. Disruption of bexA in B. thetaiotaomicron made the strain more susceptible to norfloxacin, ciprofloxacin, and ethidium bromide, showing that this gene is expressed in this organism and functions as a multidrug efflux pump. The deduced BexA protein sequence was homologous to the protein sequence of Vibrio parahaemolyticus NorM, a multidrug efflux transporter, and thus, BexA belongs to the multidrug and toxic compound extrusion (MATE) family.     

Vagus Nerve and Vagus Nerve Stimulation,a Comprehensive Review: Part II

The development of vagus nerve stimulation (VNS) began in the 19th century. Although it did not work well initially, it introduced the idea that led to many VNS‐related animal studies for seizure control. In the 1990s, with the success of several early clinical trials, VNS was approved for the treatment of refractory epilepsy, and later for the refractory depression. To date, several novel electrical stimulating devices are being developed. New invasive devices are designed to automate the seizure control and for use in heart failure. Non‐invasive transcutaneous devices, which stimulate auricular VN or carotid VN, are also undergoing clinical trials for treatment of epilepsy, pain, headache, and others. Noninvasive VNS (nVNS) exhibits greater safety profiles and seems similarly effective to their invasive counterpart. In this review, we discuss the history and development of VNS, as well as recent progress in invasive and nVNS.     

免疫荧光和免疫组化联合检测难治性癫痫患者脑组织中β类淀粉蛋白的表达

目的：β淀粉样蛋白（β-amyloid precursor protein,β-APP）是已知的参与阿尔茨海默病机制的关键因子。β-APP是否参与难治性癫痫中的病理机制并不清楚。这项研究在于了解β-APP的蛋白在难治性癫痫患者术后颞叶皮质和海马组织中的表达是否异常。方法：免疫荧光法半定量测定难治性癫痫患者术后颞叶皮质和海马组织中的β-APP阳性蛋白的荧光值,并应用统计软件对实验数据进行单因素方差分析。结果：免疫荧光强度值分析结果显示β-APP在耐药性癫痫脑组织中表达较对照组明显增高且有统计学意义。结论：pAPP在难治性癫痫脑组织中异常增高,增高的BAPP可能参与了难治性癫痫的病理机制。     

How can we best use structural information on P-glycoprotein to design inhibitors?

This year marks the 30th anniversary of the discovery of the multidrug resistance (MDR) ATP-binding cassette (ABC) transporter P-glycoprotein (P-gp). Since then a considerable research effort has attempted to provide a greater understanding of the biological enigma of "multidrug" efflux. Moreover, the growing correlation between P-gp expression and a negative prognosis or poor outcome for chemotherapy has sparked significant interest in the generation of inhibitors. How close are we to overcoming the unwanted actions of P-gp in resistant cancer following 30 years of research? The initial inhibitors were pre-existing clinically used compounds and exploited the broad specificity of P-gp. Unfortunately, the concentrations required to inhibit P-gp meant that these compounds generated considerable toxicity. Pharmacological investigations progressed to rational design using the 1st generation compounds as a template structure. Inherent toxicity of the drugs was reduced; however, pharmacokinetic interactions with the anticancer drugs were unsustainable. Generation of the most recent of inhibitors employed combinatorial chemistry to produce a handful of potent and selective P-gp inhibitors. Some of these drugs have progressed to clinical trials with poor results or in some cases, undisclosed progress. There remains a clear need for the generation of P-gp inhibitors and this review describes the potential for a structure-based design to facilitate this undertaking. In particular, the plethora of functional data can provide important regions on the protein that could conceivably be exploited as inhibitor targets.     

Fluoroquinolone resistance protein NorA of Staphylococcus aureus is a multidrug efflux transporter.

The gene of the Staphylococcus aureus fluoroquinolone efflux transporter protein NorA confers resistance to a number of structurally dissimilar drugs, not just to fluoroquinolones, when it is expressed in Bacillus subtilis. NorA provides B. subtilis with resistance to the same drugs and to a similar extent as the B. subtilis multidrug transporter protein Bmr does. NorA and Bmr share 44% sequence similarity. Both the NorA- and Bmr-conferred resistances can be completely reversed by reserpine.     

Drug transporter expression in human macrophages

Macrophages represent major cellular targets of various drugs, especially antibiotics and anti-viral drugs. Factors that may govern intracellular accumulation of drugs in these cells, especially those related to activity of drug transporters, are consequently likely important to consider. The present study was therefore designed to extensively characterize expression of solute carrier (SLC) and ATP-binding cassette (ABC) transporters in primary human macrophages generated from blood monocytes. Using quantitative polymerase chain reaction assays, these cells were found to exhibit very high or high levels of mRNA expression of concentrative nucleoside transporter (CNT) 3, equilibrative nucleoside transporter 3, monocarboxylate transporter (MCT) 1, MCT4, peptide/histidine transporter (PHT) 1, PHT2, organic anion transporting polypeptide transporter 2B1 and ABC pumps multidrug resistance protein (MRP) 1/ABCC1 and MRP3/ABCC3. By contrast, other transporters, including the efflux pump ABCB1/P-glycoprotein, were found at lower levels or were not expressed. Concomitantly, human macrophages displayed notable uptake of the MCT substrate lactate and of the CNT substrate uridine and also exhibited cellular efflux of the MRP substrate carboxy-2',7'-dichlorofluorescein. Such a functional expression of these transporters has likely to be considered with respect to cellular pharmacokinetics of drugs targeting macrophages.     

Non-PmrA-mediated multidrug resistance in Streptococcus pneumoniae

The PmrA multidrug transporter protein gene was inactivated in Streptococcus pneumoniae strains CP1000 (wild-type) and EBR (mutant with enhanced active multidrug efflux). While the resistance to fluoroquinolones and ethidium bromide shown by EBR was reduced to the wild-type level, neither the susceptibility to reserpine in the presence of ethidium bromide and selected fluoroquinolones, nor the ability to produce ethidium bromide-resistant mutants was eliminated in the CP1000 pmrA mutant, indicating the presence of an additional multidrug export protein(s).     

Reactive oxygen species involved cancer cellular specific 5-aminolevulinic acid uptake in gastric epithelial cells

Photodynamic therapy and photodynamic diagnosis using 5-aminolevulinic acid (ALA) are clinically useful for cancer treatments. Cancer cells have been reported that 5-aminolevulinic acid is incorporated via peptide transporter 1, which is one of the membrane transport proteins, and has been reported to be significantly expressed in various gastrointestinal cancer cells such as Caco-2. However, the mechanism of this protein expression has not been elucidated. Concentration of reactive oxygen species (ROS) is higher in cancer cells in comparison with that of normal cells. We have previously reported that ROS derived from mitochondria is likely related to invasions and proliferations of cancer cells. Since 5-aminolevulinic acid is the most important precursor of heme which is necessary protein for cellular proliferations, mitochondrial ROS (mitROS) may be also related to peptide transporter 1 expressions. In this study, we used a rat gastric mucosal cell line RGM1 and its cancer-like mutated cell line RGK1, and we clarified the ALA uptake mechanism and its relations between mitROS and peptide transporter 1 expression in RGK1. We also used our self-established stable clone of cell which over-expresses manganese superoxide dismutase, a mitROS scavenger. We studied differences of the photodynamic therapy effects in these cells after ALA administrations to clear the influence of mitROS.