Glucose starvation induces resistance to metformin through the elevation of mitochondrial multidrug resistance protein 1

Metformin, a drug for type 2 diabetes mellitus, has shown therapeutic effects for various cancers. However, it had no beneficial effects on the survival rate of human malignant mesothelioma (HMM) patients. The present study was performed to elucidate the underlying mechanism of metformin resistance in HMM cells. Glucose‐starved HMM cells had enhanced resistance to metformin, demonstrated by decreased apoptosis and autophagy and increased cell survival. These cells showed abnormalities in mitochondria, such as decreased ATP synthesis, morphological elongation, altered mitochondrial permeability transition pore and hyperpolarization of mitochondrial membrane potential (MMP). Intriguingly, Mdr1 was significantly upregulated in mitochondria but not in cell membrane. The upregulated mitochondrial Mdr1 was reversed by treatment with carbonyl cyanide m‐chlorophenyl hydrazone, an MMP depolarization inducer. Furthermore, apoptosis and autophagy were increased in multidrug resistance protein 1 knockout HMM cells cultured under glucose starvation with metformin treatment. The data suggest that mitochondrial Mdr1 plays a critical role in the chemoresistance to metformin in HMM cells, which could be a potential target for improving its therapeutic efficacy.     

2017年安徽省某三甲医院细菌耐药性监测

目的 了解铜陵市人民医院2017年临床分离细菌对抗菌药物的耐药状况。方法 对2017年1-12月临床分离菌采用纸片扩散法(KB)进行药敏试验，按CLSI 2017年版标准判读药敏试验结果，采用WHONET 5.6软件进行数据分析。结果 临床分离细菌共3436株，其中革兰阳性菌719株，占20.9%；革兰阴性菌2717株，占79.1%。耐甲氧西林金黄色葡萄球菌(MRSA)和耐甲氧西林凝固酶阴性葡萄球菌(MRCNS)的检出率分别为23.8%和72.3%，耐甲氧西林株对β-内酰胺类抗生素和其他测试抗菌药物的耐药率显著高于甲氧西林敏感株，未发现对万古霉素和替考拉宁耐药的葡萄球菌。粪肠球菌对青霉素、氨苄西林和呋喃妥因的耐药率较低，屎肠球菌对氯霉素的耐药率较低，5.3%屎肠球菌对万古霉素耐药。大肠埃希菌、克雷伯菌属(肺炎克雷伯菌和产酸克雷伯菌)和奇异变形菌中ESBLs的检出率分别为41.4%、50.7%和19.4%。肠杆菌科细菌中克雷伯菌属和沙雷菌属对碳青霉烯类抗生素耐药率较高，分别为37.5%和36.0%，其他菌属的耐药率低于3%。鲍曼不动杆菌对亚胺培南和美罗培南的耐药率分别80.3%和79.1%；铜绿假单胞菌对亚胺培南和美罗培南的耐药率分别为29.7%和28.4%。肺炎克雷伯菌、鲍曼不动杆菌和铜绿假单胞菌中广泛耐药株的检出率分别为31.3%(171/546)、0.6%(3/508)和0.7%(3/416)。结论 本院革兰阴性菌呈增多趋势，尤其广泛耐药的肺炎克雷伯菌应引起高度关注，做好细菌耐药性监测，加强临床抗菌药物的合理使用和医院感染控制。     

Investigation of non-linear Mate1-mediated efflux of trimethoprim in the mouse kidney as the mechanism underlying drug-drug interactions between trimethoprim and organic cations in the kidney

The purpose of this study was to elucidate the involvement of Mate1 in the tubular secretion of trimethoprim and saturation of Mate1-mediated efflux to address the mechanisms underlying the pharmacokinetic drug interactions with trimethoprim. Trimethoprim is a more potent inhibitor of MATE2-K than MATE1 with K_i values (μM) of 0.030–0.28 and 2.4–5.9, respectively. Trimethoprim is a substrate of human MATE1 and MATE2-K with K_m values of 2.3 ± 0.9 and 0.018 ± 0.004 μM, and mouse Mate1, but not human OCT2, mouse Oct1 and Oct2. Pyrimethamine significantly reduced the renal clearance (CL_R) of trimethoprim (mL/min/kg) from 40.0 ± 5.1 to 20.1 ± 3.7 (p < 0.05). Trimethoprim was given to mice at three infusion rates (150, 500, and 1500 nmol/min/kg). Together with an increase in the plasma concentrations of trimethoprim, the CL_R (mL/min/kg) of trimethoprim decreased to 25.9 ± 3.2, 13.5 ± 5.7, and 8.92 ± 1.50 at the respective rates. Trimethoprim decreased the CL_R of rhodamine 123 in an infusion rate-dependent manner: 11.5 ± 1.3 (control), 5.17 ± 1.55, 1.31 ± 0.50, and 0.532 ± 0.180. These results suggest that Mate1 mediates the tubular secretion of trimethoprim, and at therapeutic doses, MATEs-mediated efflux can be saturated, and thereby, cause drug interactions with other MATE substrates.     

肝癌多药耐药产生与低糖环境的关系

目的探讨局部微环境低糖与肝细胞癌多药耐药性(MDR)产生的关系及影响机制。方法低糖培养HepG2细胞,应用流式细胞术Annexin V/PI法检测低糖培养的细胞在化疗药物5-氟脲嘧啶(5-Fu)作用后的凋亡情况,分别应用荧光定量聚合酶链反应(PCR)技术和Western blot技术检测低糖培养后HepG2细胞内多药耐药相关基因mdr1、MRP1、LRP的mRNA和蛋白水平的表达。结果在低糖环境下生长时间越长的HepG2细胞对5-Fu的抵抗越强,而且随着低糖培养时间的增加,5-Fu诱导的HepG2细胞的凋亡高峰延迟。低糖培养的HepG2细胞内多药耐药相关基因mdr1、MRP1、LRP在mRNA和蛋白水平的表达随低糖培养时间的延长而升高,以LRP的改变最为显著。结论肝癌生长微环境葡萄糖耐量不足也是肝癌产生MDR的原因之一。低糖可通过上调一组多药耐药相关基因的表达而诱导肝癌的多药耐药性。     

应用质粒分析探讨医院内细菌感染的流行病学特点

为探讨医院内细菌感染的流行病学特点，作者借助临床分离的６４株肺为克雷伯菌，４５株阴沟肠杆菌和６３株醋酸钙不动杆菌，进行质粒图谱分３种细菌分别有５８株，３５株和４１株含有质粒，且分别构成４６个，２１个和２３个质粒图谱型。结果表明：质粒分析为查明医院内细菌感染源和感染途径提供了较为直接，准确的客观依据，同时也看到了质粒分析的局限性。     

A study of the value of electrophoretic and other techniques for typing Acinetobacter calcoaceticus

Forty-four isolates of Acinetobacter calcoaceticus var anitratus collected during hospital outbreaks were studied using polyacrylamide gel electrophoresis (PAGE), plasmid analysis, antibiograms and biochemical tests to determine their degree of similarity. Reproducibility tests were also carried out on the PAGE and biochemical techniques to determine their validity when used to compare bacteria of the same type isolated intermittently. PAGE data was analysed densitometrically and isolates compared using a similarity matrix. All methods were able to subdivide the isolates, but results did not always correlate well between methods. Reproducibility data indicated that careful attention to technique is required when organisms are examined by PAGE sequentially. Results suggest that no single biotyping technique is likely to be adequate and that electrophoretic, biochemical and antibiogram data may complement one another and other epidemiological data in the typing of these organisms.