Clonality among ampicillin-resistant Enterococcus faecium isolates in Sweden and relationship with ciprofloxacin resistance

Objective  To investigate clonal relationships in a nationwide sample of human Enterococcus faecium isolates.
Methods  Biochemical fingerprinting (PhP (PhenePlate) typing) was used to compare 180 fecal ampicillin-resistant E. faecium (ARE) isolates with 169 matched fecal ampicillin-susceptible E. faecium (ASE) isolates from patients in 23 hospitals, collected in 1998, and to study 39 fecal ARE isolates from non-hospitalized individuals collected in 1998, and five ARE and 29 ASE isolates from the early 1990s. Representative ARE and ASE isolates were subjected to pulsed-field gel electrophoresis (PFGE) analysis of genomic DNA and sequencing of the regions encoding the fluoroquinolone targets of the enzymes GyrA and ParC.
Results  Both PhP and PFGE results showed a higher homogeneity among ARE than among ASE isolates ( P  < 0.001). One PhP type (FMSE1) comprised 73% of the hospital ARE isolates (53% of ARE isolates from non-hospitalized individuals, and four of five ARE isolates from the early 1990s), but only 1% of the ASE isolates. PFGE of the hospital E. faecium isolates revealed that 23 of the 25 ARE isolates and one of the 22 ASE isolates were of one dominating type. High-level resistance to ciprofloxacin (MIC > 16 mg/L) was present in 91% of ARE isolates, whereas only low-level resistance (MIC 4–16 mg/L; 35% of isolates) was found among ASE isolates. One mutation in parC (codon 80) and one of two mutations in gyrA (codons 83 or 87) were detected in all ARE isolates tested with high-level ciprofloxacin resistance, but were lacking in ARE and ASE isolates with low-level ciprofloxacin resistance.
Conclusion  Most ARE isolates in Sweden were clonally related. High-level ciprofloxacin resistance was found in ARE isolates of PhP type FMSE1 as well as in other PhP types, but never in ASE isolates.     

Immunomodulatory activity of Asparagus racemosus on systemic Th1/Th2 immunity: Implications for immunoadjuvant potential

Ethnopharmacological relevance

Roots of Asparagus racemosus Willd (Shatavari in vernacular) are widely used in Ayurveda as Rasayana for immunostimulation, galactogogue as also in treatment of conditions like ulcers and cancer. Various studies have indicated immunomodulatory properties of Shatavari root extracts and formulations.

Aim of the study

To study the effect of standardized Asparagus racemosus root aqueous extract (ARE) on systemic Th1/Th2 immunity of SRBC sensitized animals.

Materials and methods

We used HPTLC to quantify steroidal saponins (Shatavarin IV, Immunoside^®) and flow cytometry to study effects of ARE on Th1/Th2 immunity. SRBC specific antibody titres and DTH responses were also monitored as markers of Th2 and Th1 responses, respectively. We also studied lymphocyte proliferation. Cyclosporin, cyclophosphamide and levamisole were used as controls.

Results

Treatment with ARE (100 mg/(kg b.w. p.o.)) resulted in significant increase of CD3⁺ and CD4/CD8⁺ percentages suggesting its effect on T cell activation. ARE treated animals showed significant up-regulation of Th1 (IL-2, IFN-g) and Th2 (IL-4) cytokines suggesting its mixed Th1/Th2 adjuvant activity. Consistent to this, ARE also showed higher antibody titres and DTH responses. ARE, in combination with LPS, Con A or SRBC, produced a significant proliferation suggesting effect on activated lymphocytes.

Conclusion

The study suggests mixed Th1/Th2 activity of ARE supports its immunoadjuvant potential.     

Nrf2/ARE信号通路及其相关药物研究进展

Nrf2/ARE信号通路是细胞氧化应激反应中的关键通路,其调控的下游抗氧化蛋白和Ⅱ相解毒酶在细胞防御保护中发挥重要作用。现有研究显示Nrf2/ARE通路在抗炎、抗肿瘤、神经保护、抗凋亡等多方面具有重要作用,以Nrf2为靶点的药物有望用于多发性硬化、糖尿病、神经退行性疾病、肿瘤等多种疾病的治疗,其中已有富马酸二甲酯、巴多克沙龙等多个新药进入临床研究阶段。就Nrf2/ARE通路与疾病的关系及以其为靶点的新药研发进展做一综述。     

酰化4-羟基查耳酮对H2O2诱导的PC12细胞凋亡的抗氧化保护作用及初步机制

目的:研究查尔酮化合物B1、B2对过氧化氢(H2O2)诱导的PC12细胞凋亡的保护作用及其对Nrf2/ARE信号通路的影响。方法:建立H2O2诱导PC12细胞氧化损伤的模型,用MTT法检测化合物B1和B2的抗氧化活性及细胞毒性;用实时荧光定量PCR(real-time PCR)法检测其对转录相关因子Nrf2调控基因谷氨酰半胱氨酸合成酶催化亚单位(GCLC)、血红素氧合酶-1(HO-1)m RNA表达的影响;用Hoechst染色检测其对H2O2诱导的PC12细胞凋亡的抑制作用。结果:分别加了B1、B2的细胞孵育1 h后,B1、B2对H2O2诱导的PC12细胞氧化损伤无保护作用,而孵育24 h后,B1、B2均具有较好的保护作用,两者在浓度为10μmol/L时对细胞无毒性;B1对Nrf2下游GCLC、HO-1基因的表达无明显影响,而B2可明显激活GCLC、HO-1基因的表达,且明显抑制H2O2诱导的PC12细胞的凋亡。结论:B1、B2均对H2O2诱导的PC12细胞损伤具有较好的抗氧化保护作用,B2的作用机制可能是通过激活Nrf2/ARE抗氧化信号通路来实现,B1可能是通过其他机制起到抗氧化作用。     

基于Nrf2/ARE信号通路探讨硫氢化钠对溃疡性结肠炎大鼠肠黏膜损伤的影响

目的 基于Nrf2/ARE信号通路探讨硫氢化钠对溃疡性结肠炎（UC）大鼠肠黏膜损伤的影响。方法将27只UC大鼠随机分为模型组、阳性对照组及硫氢化钠组,每组9只,另取8只正常大鼠为对照组。阳性对照组大鼠于模型复制成功后第3天给予柳氮磺胺吡啶（SASP）混悬溶液0.5 g/（kg·d）灌胃给药,硫氢化钠组大鼠于同时间腹腔注射1 mL硫氢化钠溶液（100μmol/L,1次/d,连续7 d）,模型组和对照组于同时间腹腔注射等量生理盐水,观察大鼠一般情况。酶联免疫吸附试验检测白细胞介素-8(IL-8)、肿瘤坏死因子-α(TNF-α)水平;苏木精-伊红染色观察大鼠结肠组织病理学变化;Western blotting检测大鼠结肠组织中核因子E2相关因子2/抗氧化反应元件（Nrf2/ARE）信号通路蛋白水平的变化。结果 与对照组比较,模型组、阳性对照组及硫氢化钠组大鼠血清IL-8水平、TNF-α水平升高（P <0.05）;与模型组比较,阳性对照组和硫氢化钠组大鼠血清IL-8水平、TNF-α水平降低（P <0.05）。模型组、阳性对照组及硫氢化钠大鼠结肠黏膜组织CMDI评分比较,差异有统计学...     

The emerging role of the Nrf2–Keap1 signaling pathway in cancer

The Nrf2 (nuclear factor erythroid 2 [NF-E2]-related factor 2 [Nrf2])–Keap1 (Kelch-like erythroid cell-derived protein with CNC homology [ECH]-associated protein 1) signaling pathway is one of the most important cell defense and survival pathways. Nrf2 can protect cells and tissues from a variety of toxicants and carcinogens by increasing the expression of a number of cytoprotective genes. As a result, several Nrf2 activators are currently being tested as chemopreventive compounds in clinical trials. Just as Nrf2 protects normal cells, studies have shown that Nrf2 may also protect cancer cells from chemotherapeutic agents and facilitate cancer progression. Nrf2 is aberrantly accumulated in many types of cancer, and its expression is associated with a poor prognosis in patients. In addition, Nrf2 expression is induced during the course of drug resistance. Collectively, these studies suggest that Nrf2 contributes to both intrinsic and acquired chemoresistance. This discovery has opened up a broad spectrum of research geared toward a better understanding of the role of Nrf2 in cancer. This review provides an overview of (1) the Nrf2–Keap1 signaling pathway, (2) the dual role of Nrf2 in cancer, (3) the molecular basis of Nrf2 activation in cancer cells, and (4) the challenges in the development of Nrf2-based drugs for chemoprevention and chemotherapy.     

知柏地黄汤通过调节ARE信号通路激活细胞抗氧化反应治疗阴虚火旺证的机制研究

[目的]通过研究知柏地黄汤对细胞抗氧化反应元件(antioxidant response element,ARE)信号通路的调节及其对大鼠血清代谢物的干预作用,探讨其治疗阴虚火旺证的可能机制。[方法]将人肝癌细胞系HepG2细胞分为对照组、知柏地黄汤低、中、高浓度组,分别以0、1、20和100mg·mL-1的知柏地黄汤干预24h,通过双萤光素酶报告基因实验筛选知柏地黄汤显著调控的信号通路;荧光定量PCR检测所筛选通路相关基因的表达,并利用磷钼酸比色法及氧化酶法检测细胞内三磷酸腺苷(adenosine triphosphate,ATP)含量、细胞耗氧率(oxygen consumption rate,OCR)、超氧化物歧化酶(superoxide dismutase,SOD)活性的变化。45只SD大鼠随机分成3组,空白组以0.9%氯化钠溶液灌胃21d,干姜组先以10g·kg-1干姜附子肉桂汤灌胃14d、再以0.9%氯化钠溶液灌胃7d,干知组先以10g·kg-1干姜附子肉桂汤灌胃14d、再以知柏地黄汤灌胃7d,灌胃体积为10mL/(kg·d),以液相色谱-质谱联用(liquid chromatography-mass spectrometry,LC-MS)技术检测血清中代谢物的改变。[结果]双萤光素酶报告基因实验显示,知柏地黄汤对ARE元件调控最为显著,荧光定量PCR结果显示知柏地黄汤可以促进核因子红细胞2相关因子2(nuclear factor erythroid-2-related factor 2,Nrf2)、小肌腱膜纤维肉瘤(musculoaponeurotic fibrosarcoma,Maf)的转录(P0.001,P0.05),同时抑制Kelch样ECH相关蛋白1(Kelch-like ECH-associated protein1,Keap1)的转录(P0.001)。与对照组比较,知柏地黄汤组细胞ATP含量(P0.05)、OCR(P0.001)及SOD活性(P0.05)均升高。动物实验证实,知柏地黄汤灌胃治疗可以改善阴虚火旺模型大鼠胆碱、甘胆酸及棕榈酰左旋肉碱(palmitoyl-L-carnitine,PALC)的紊乱,其中胆碱及PALC含量差异有统计学意义(P0.001)。[结论]知柏地黄汤能够通过ARE信号通路,抑制机体的氧化应激反应,进而改善阴虚火旺引起的代谢紊乱,这可能是知柏地黄汤治疗阴虚火旺证的作用机制之一。     

Neurotoxic effects of iron overload under high glucose concentration

Iron overload can lead to cytotoxicity, and it is a risk factor for diabetic peripheral neuropathy. However, the underlying mechanism remains unclear. We conjectured that iron overload-induced neurotoxicity might be associated with oxidative stress and the NF-E2-related factor 2 （Nrf2）/ARE signaling pathway. As an in vitro cellular model of diabetic peripheral neuropathy, PC12 cells ex- posed to high glucose concentration were used in this study. PC12 cells were cultured with ferric ammonium citrate at different concentrations to create iron overload. PC12 cells cultured in ferric ammonium citrate under high glucose concentration had significantly low cell viability, a high rate of apoptosis, and elevated reactive oxygen species and malondialdehyde levels. These changes were dependent on ferric ammonium citrate concentration. Nrf2 mRNA and protein expression in the ferric ammonium citrate groups were inhibited markedly in a dose-dependent manner. All changes could be inhibited by addition of deferoxamine. These results indicate that iron overload aggravates oxidative stress injury in neural cells under high glucose concentration and that the Nrf2/ARE sigfnaling pathway might play an important role in this process.