摘要
目的：观察小剂量脂多糖（LPS）对人脐静脉内皮细胞（ECV304）TOLL样受体4（TLR4）表达的影响。方法：体外培养ECV304细胞,分别与LPS及LPS＋TLR4抗体进行孵育。MTT法检测细胞的增殖活性,免疫组化染色法检测细胞表面TLR4的表达,实时荧光定量聚合酶链反应（RT-PCR）检测细胞核核内TLR4-mRNA及IL-8mRNA的表达。结果：LPS（10～50ng/mL）刺激ECV304细胞24h内,细胞增殖活性无明显变化（P〉0.05）;而以100ng/mL刺激24h后,细胞增殖活性明显降低（P〈0.05）,TLR4抗体对此无明显拮抗作用。LPS能明显上调ECV304表达TLR4、TLR4-mRNA及IL-8mRNA,其中10ng/mL的LPS在24h时、50ng/mLLPS在6～24h时,TLR4表达具有统计学意义（P〈0.05）;50ng/mL的LPS刺激ECV304细胞在4h及8h时,细胞核内TLR4mRNA表达均明显升高（P〈0.05）,而IL-8mRNA表达在8h时明显升高（P〈0.05）。TLR4抗体对ECV304表达TLR4及TLR4-mRNA有拮抗作用（P〈0.05）,对IL-8mRNA表达无明显拮抗作用（P〉0.05）。结论：小剂量LPS可诱导ECV304细胞表达TLR4并引起细胞活化,TLR4抗体可抑制TLR4的表达,但不能抑制细胞的活化。
To solve the system performance deteriorating problem caused by too lar ge variable range of signal power in receiver,this paper proposes an IF large d ynamic automatic gain control method with 70dB dynamic range based on IF signal detection voltage feedback and 2-stage AD8368 chip cascade structure.The analys is on closed loop control circuit proves that this method can solve the automati c control problem of signal gain within wide dynamic range,achieve fast,stable and automatic gain control,ensure high sensitivity of receiver under small sig nal conditions and improve the system of received sensitivity.
出处
《无线电工程》
2012年第4期47-50,共4页
Radio Engineering
