P-糖蛋白在血脑屏障中的作用

1970年,Biedler等在放线菌素处理的中国仓鼠细胞和小鼠白血病P388细胞中首先发现多药耐药（MDR）现象;继之,Juliano等在中国仓鼠卵巢细胞MDR株的细胞膜上分离出一种磷酸糖蛋白,即P-糖蛋白（P-gp）。     

P-糖蛋白与血脑屏障

P-糖蛋白是ATP结合盒转运超家族成员之一,在体内许多部位均有表达,与多药耐药性有关。作为一种外排泵,血脑屏障内的P-糖蛋白能排出内源性底物和外源性化学物质以保持脑内环境的稳定,但同时也限制了治疗性药物在脑内的浓度,从而使治疗效果减弱。P-糖蛋白抑制剂可促进药物通过血脑屏障,对提高脑内药物的浓度和中枢神经系统药物的生物利用度具有重要意义。     

血脑屏障ATP结合盒超家族转运蛋白与药物转运

血脑屏障ATP结合盒(ATP—bmding cassette，ABC)超家族转运蛋白对维护血脑屏障的完整性、保持脑内环境的稳定和药物转运等方面都起着重要作用。文章主要就ABC超家族转运蛋白，如P-糖蛋白、多药耐药蛋白和乳癌耐药蛋白在血脑屏障药物转运中的作用做了综述。     

P-糖蛋白抑制剂的研究进展

多药耐药是由于一系列没有相关性且结构及功能不同的肿瘤化疗药物的频繁临床使用而产生的,它是临床上肿瘤化疗失败的主要原因之一[1-2]。多药耐药的产生机制很多,其中研究最为广泛的机制就是多药耐药基因1（MDR1）基因编码,依赖于三磷酸腺苷（ATP）供能,     

P-糖蛋白与难治性癫痫的关系

P-糖蛋白(Pgp)已成为目前难治性癫痫耐药机制研究的靶点之一.随着对Pgp研究的深入,Pgp结构、功能及其过度表达与癫痫耐药机制逐渐被阐明,Pgp抑制剂的研究也为治愈难治性癫痫开拓了新的方向.该文就有关这方面的研究进展作一综述.     

血脑屏障ATP结合盒超家族转运蛋白与药物转运

血脑屏障ATP结合盒(ATP-bindingcassette,ABC)超家族转运蛋白对维护血脑屏障的完整性、保持脑内环境的稳定和药物转运等方面都起着重要作用。文章主要就ABC超家族转运蛋白,如P-糖蛋白、多药耐药蛋白和乳癌耐药蛋白在血脑屏障药物转运中的作用做了综述。     

扎里奴思方对局灶性脑缺血再灌注损伤大鼠P-糖蛋白的影响

目的比较缺血损伤不同时段大鼠血脑屏障P-糖蛋白(P-gp)时征表达及回药扎里奴思方对其表达的影响。方法 SD大鼠随机分为假手术组、模型组、尼莫地平组、扎里奴思方组,线栓法制备脑缺血再灌注模型,分别灌胃给药,于缺血再灌注后1、3、7、14 d取脑,检测大鼠脑皮质及海马区P-gp的表达。结果免疫组织化学染色结果显示,假手术组与模型组大鼠脑皮质及海马缺血区均可见P-gp阳性染色。与假手术组比较,不同再灌注时间模型组P-gp表达量均有显著性差异(P0.01),皮质及海马缺血区P-gp表达量均升高;与模型组比较,扎里奴思方组及尼莫地平组大鼠脑皮质及海马区P-gp表达量明显降低,尤以扎里奴思方3、14 d组为明显(P0.01)。结论扎里奴思方发挥抗脑缺血损伤、神经元保护作用机制可能是通过调节血脑屏障上P-gp的双向表达而实现的。     

选择性环氧合酶-2抑制剂NS-398抑制胃癌细胞P-糖蛋白表达

目的 探讨选择性环氧合酶-2（COX-2）抑制剂NS-398对胃癌细胞株SGC-7901 P-糖蛋白（P-gp）表达的影响。方法 胃癌细胞株SGC-7901经浓度分别为0、10、100μmol／L的NS-398处理后，酶联免疫吸附试验检测NS-398对胃癌细胞前列腺素E2（PGF2）分泌的影响，24、48h后用RT-PCR检测多药耐药（mdr）1 mRNA表达，48h后用免疫细胞化学染色法检测P-gp表达。结果 NS-398可显著抑制胃癌细胞株SGC-7901 PGE2分泌，并呈浓度依赖性（P〈0．05）。不同浓度NS-398作用于细胞后，胃癌细胞株SGC-7901的mdr1／P-gp表达受不同程度抑制，100μmol／L的NS-398对mdr1 mRNA表达抑制作用强于10μmol／L（P〈0．01）。不同浓度药物与测量时间为交互作用．作用48h与24h相比，NS-398对mdr1 mRNA表达的抑制作用更强（P〈0．01）。结论 NS-398可抑制SGC-7901的mdr1／Pgp表达，且呈剂量效应关系。NS-398可能通过抑制COX-2活性，抑制COX-2下游产物PGE2表达，从而抑制P-gp表达。选择性COX-2抑制削可能有助于减轻肿瘤细胞对化疗药物的耐药性。     

脂质体两性霉素B的研究及临床应用现状

脂质体两性霉素B(L AmB)作为两性霉素B的一种新剂型 ,试用于临床已有 1 0余年的历史。与传统的两性霉素B(AmB)相比 ,L AmB的抗菌效能相当而毒副作用显著降低 ,特别是对于AmB治疗无效或不能耐受的病例 ,L AmB表现出了良好的治疗前景。所以 ,自L AmB试用于临床以来 ,受到了广泛的关注。有关的基础研究和临床报告不断增多 ,本文对L AmB的研究及临床应用现状进行了综述。     

凝血酶对血脑屏障通透性影响及其机制的实验研究

目的　探讨凝血酶 (TB)对血脑屏障通透性的影响及其可能机制。　方法　将TB或TB +组织蛋白酶G(CT G)立体定向注入SD大鼠右侧基底节 ,测定其血脑屏障通透性和脑水含量 ;将脑微血管内皮培养液中加入TB或TB +CT G ,相差显微镜动态观察内皮细胞形态的变化 ,免疫组织化学技术检测基质金属蛋白酶 2 (MMP 2 )表达的改变。　结果　TB脑内注射后 6h ,同侧基底节区血脑屏障通透性为 (0 4 19± 0 0 16 )A/mg (P <0 0 5 ) ,2 4h时血脑屏障通透性为 (0 5 94± 0 0 18)A/mg(P <0 0 1) ,持续至 4 8h (P <0 0 5 )逐渐消退 ,脑组织水含量的变化规律与血脑屏障通透性的变化类似。TB +CT G组在各个时间点血脑屏障通透性和脑组织水含量与对照组比较差异均无显著性 (P >0 0 5 )。TB使内皮细胞发生收缩 ,细胞收缩程度具有时间依赖性。TB入培养液 6h后 ,内皮细胞MMP 2表达水平为 (0 391± 0 0 17)A ,与对照组比较差异有显著性 (P <0 0 1)。TB +CT G加入培养液后 ,细胞形态、MMP 2表达与对照组比较差异均无显著性 (P >0 0 5 )。　结论　TB增加血脑屏障通透性是其诱发脑水肿形成的主要机制之一 ,TB通过激活蛋白酶激活受体 1(PAR 1) ,使内皮细胞发生收缩 ,促进MMP 2表达 ,是TB增加血脑屏障通透性的可能机制     

A quantitative evaluation of the permeability of the blood brain barrier of portacaval shunted rats

The integrity of the blood-brain barrier (BBB) was measured in male Sprague Dawley rats subjected to 16 weeks of portacaval shunting (PCS), the optimal time required for the cerebral changes to develop, by using anin situ brain perfusion technique. The penetration of a vascular space marker¹⁴C mannitol, and labelled amino acids³H-phenylalanine or³H-glutamate were measured in brain and cerebrospinal fluid (CSF) using anin situ brain perfusion technique, over 2 or 20 minutes. The patency of the surgical shunt was confirmed by measurement of significantly increased plasma ammonia (131.5±14.8 μ mol.l⁻¹) and AST (159.5±19.9 IU.l⁻¹) concentrations compared to controls 39.9±3.7^*, and 82.5±6.6^* respectively. Brain and CSF¹⁴C-mannitol space (ml. 100g⁻¹), was not increased by PCS where brain space was 1.31±0.27 mL. 100g⁻¹ compared to control 1.19±0.49 mL. 100g, control n=8). The uptake for³H-glutamate, which is required for cerebral ammonia detoxification, was also unchanged in both brain and CSF. However, brain uptake of³H-phenylalanine was significantly reduced from 871 ±80 μL. min⁻¹.g⁻¹ to 356±154^* μl.min⁻¹.g⁻¹ (n=4), although there was no change in CSF uptake. These data suggest that there is no generalized breakdown of the blood-brain or blood-CSF barriers during PCS as assessed by mannitol penetration. The reduction in phenylalanine uptake into the brain may help stabilize high cerebral aromatic amino acid levels.^*P<0.05, Two-tailed, Student’s unpaired t-test.     

Toll受体4在急性胰腺炎引起的血-脑脊液屏障通透性增高中的作用

目的 研究Toll受体4(toll receptor-4,TLR-4)在急性胰腺炎(AP)合并中枢神经系统(CNS)损伤中的作用.方法 将64只SD大鼠分为8组:对照组;急性水肿性胰腺炎(AEP)2、6 h组;急性坏死性胰腺炎(ANP)2、6、12、24、48 h组,每组8只.测定血-脑脊液屏障(BBB)通透性、胰腺病理损伤程度、组织TLR-4的表达,并分析其相互关系.结果 对照组,AEP2、6 h组,ANP 2、6、12、24、48 h组的BBB通透性分别为1.55±0.29、1.64±0.17、1.69±0.24、1.89±0.12、2.66±0.32、2.91.4±0.29、2.89±0.69和1.84±0.07;胰腺病理分值分别为0、2.38±0.92、3.13±0.64、8.50±1.07、9.75±0.71、10.25±1.28、1 1.13±1.25和10.13±1.13.AEP组与对照组无显著筹异,ANP各组较AEP组显著升高(P＜0.05或P＜0.01).BBB通透性与胰腺损伤呈正相关(r=0.626,P＜0.01).对照组和AEP组无TLR-4mRNA和蛋白表达,而ANP各组明显表达,其表达水平与BBB通透性水平呈正相关(r=0.208,P=0.027).结论 ANP时存在BBB通透性的升高,CNS内TLR-4信号途径的激活可能参与了ANP所引起的血-脑脊液屏障通透性的升高.     

两性霉素B治疗侵袭性真菌感染回顾性研究

目的评估两性霉素B（AmB）治疗侵袭性真菌感染的安全性、有效性及经济性。方法回顾性分析AmB优化生产工艺前后两年时间内侵袭性真菌感染住院治疗患者113例临床资料。结果临床有效率为76％以上。不良反应中,低钾血症发生率为33．6％、肌酐（Cr）、尿素氮（BUN）一过性升高发生率分别为29．0％和27．4％,发热等即刻反应总发生率为15．0％;未发现归因于AmB导致的死亡和不可逆的肾功能损害。工艺改进后,过敏等即刻反应明显下降（发生率由28．0％降至7．2％）。以感染性心内膜炎、骨髓炎、隐球菌脑膜炎等疾病为例,按12周标准疗程和常规剂量静脉注射计算费用,AmB的治疗费用约为4600元,氟康唑（进口）为38000元,伊曲康唑为99100元,AmB脂质体为190000元,伏立康唑为250000元,醋酸卡泊芬净为270000元。结论AmB仍是目前抗真菌药物中疗效最佳者;生产工艺改进后发热等即刻不良反应的发生率显著减少;绝大部分患者可以完成治疗,获得治愈;其明显的药效-经济学优势在侵袭性真菌感染特别是需长期治疗的疾病中具有不可替代的作用和地位。     

Acute immune hemolysis induced by a degradation product of amphotericin B

Summary We report here on an eight-year-old boy who first developed acute intravascular hemolysis following therapy with amphotericin B (AmB) and subsequently a delayed hemolytic transfusion reaction due to alloantibodies. Although there is as yet no evidence for metabolism of AmB in vivo, the hemolysis appeared to be the result of sensitization against a degradation product of the drug. The patient's serum contained a hemagglutinating IgM antibody that reacted with all red blood cells (RBC) tested in the presence of plasma obtained from patients receiving AmB (ex vivo antigen), but not in the presence of their urine, AmB itself, or with AmB-pretreated RBC. These findings indicate that the antibody was directed against a degradation product of AmB, presumably a trace metabolite, that has not yet been identified.     

Effects of amphotericin B on isolated rabbit hearts.

The effects of amphotericin B on contraction and electrical activity of isolated rabbit hearts were tested. The hearts were perfused with Krebs Henseleit solution at 33°C and constant coronary flow. Amphotericin B was used at concentrations of 1.25, 2.5, 5 and 10 μg/ml. Surface electrograms were displayed synchronously with atrial transmembrane potentials. In non-driven preparations, amphotericin caused progressive lengthening of PR interval and P wave. AV conduction block progressed towards complete atrioventricular dissociation. The effects were the same with all the concentrations used but the time course of the changes observed was related to the concentration. In driven preparations, the antibiotic produced a decrease in action potential amplitude. This was characterized by the progressive abolition of the slow phase of depolarization followed by a decrease in the amplitude of the fast phase of the upstroke. The maximum depolarization rate decreased. Progressive inactivation of atrial fibers occurred. Alternance of action potentials with electrotonic potentials was currently observed. Finally, the preparation became irreversibly unexcitable. It is proposed that amphotericin exerts its effects by progressive blocking of the ionic currents involved in excitation, and that it also interferes with the processes of activation and removal of inactivation.     

Successful treatment of disseminated candidiasis resistant to amphotericin B by liposomal amphotericin B: a case report

The case of a female patient with acute lymphoblastic leukaemia and chronic disseminated candidiasis, who was refractory to 1.8 g conventional amphotericin B therapy, is reported. She experienced severe amphotericin-B-related side-effects in spite of pretreatment, but was subsequently successfully treated with 3 g of a small unilamellar liposome formulation of amphotericin B prepared from soya phosphatidylcholine and cholesterol in a 73 molar ratio at our institute. The patient experienced minimal side-effects with this preparation, although no pretreatment was given. Liposomal amphotericin B prepared in our institute appears to be a safe and effective therapy for systemic fungal infections. However, large controlled studies are required to determine more precisely the potential of liposomal amphotericin B in the treatment of severe systemic fungal infection.     

国产两性霉素B治疗恶性血液病并发肺部真菌感染38例临床观察

目的:探讨国产两性霉素B对恶性血液病并发肺部真菌感染的疗效和安全性。方法:对河南省肿瘤医院血液科2001年12月~2005年12月期间经微生物学和临床资料证实的38例肺部真菌感染患者,随机分为2组(传统给药组即逐步加量组和改良给药组即起始足量组)接受国产两性霉素B治疗,观察2组疗效及不良反应。结果:38例应用国产两性霉素B患者中有3例因严重药物不良反应停药,其余35例患者比较显示改良给药组达显效时间短于传统给药组,2组间总体疗效及不良反应差异无统计学意义。结论:一开始即给足够剂量的国产两性霉素B治疗恶性血液病并发肺部真菌感染达显效时间短于逐渐加药的给药方法,其不良反应及总体疗效与后者差异无统计学意义。     

Aerosol amphotericin B inhalations for prevention of invasive pulmonary aspergillosis in neutropenic cancer patients

To determine the value of aerosol amphotericin B inhalations for prevention of invasive pulmonary aspergillosis (IPA), we initiated a prospective randomized multicenter trial. The scheduled intent-to-treat interim analysis included 115 patients (30%) with prolonged neutropenia after chemotherapy for acute myeloid leukemia, acute lymphoblastic leukemia/high-grade non-Hodgkin's lymphoma, or solid tumors undergoing autologous stem cell transplantation. Sixty-five patients had been randomized to receive prophylactic aerosol amphotericin B inhalations at a dose of 10 mg twice daily (group A); for the remaining 50 patients no aerosol amphotericin B prophylaxis was used (group B). No serious side effects from amphotericin B inhalations occurred, but coughing (54%), bad taste (51%), and nausea (37%) caused early cessation of aerosol amphotericin B prophylaxis in 23% (15/65) of courses. In group A, the incidence of proven, probable, or possible IPA was 5% (3/65) as compared with 12% (6/50) in group B (p>0.05). Microbiologically documented bacterial pneumonias were observed in 5/65 (8%) patients in group A and in 1/50 (2%) patients in group B (p>0.05). Thus, no reduction in incidence of IPA from use of prophylactic aerosol amphotericin B inhalations was found in this interim analysis. As there were no serious side effects from aerosol amphotericin B prophylaxis, accrual in the study will continue for a total of 380 patients.     

Influence of amphotericin B on the transport of phosphate, sulphate and potassium ions across the human erythrocyte membrane

Some effects of the clinically important fungicidal antibiotic amphotericin B on the transport of phosphate, sulphate and potassium ions across the membrane of the human erythrocyte were investigated. In general, amphotericin B inhibited the transport of the anions to about the same degree and stimulated the transport of the cation. At low concentrations, the inhibition of both phosphate and sulphate ion transport was concentration-dependent. A plateau was reached at 47 and 52% transport for phosphate and sulphate, respectively, beyond which no further inhibition was obtained. In contrast, the initial rate of potassium ion release from erythrocytes was stimulated. This effect was also concentration-dependent. The observed stimulatory effect on cation efflux was attributed to penetration of the antibiotic into the membrane of the erythrocyte, leading to the formation of specific channels. The inhibition of transport of anions, however, was attributed to alteration in the fluidity of the lipid bilayer consequent to channel formation.