Synthesis of polyribonucleotide chains from the 3'-hydroxyl terminus of oligodeoxynucleotides by Escherichia coli primase

Escherichia coli primase synthesizes RNA primers on DNA templates for the initiation of DNA replication. The sole known activity of primase is to catalyze synthesis of short RNA chains de novo. We now report a novel activity of primase, namely that it can synthesize RNA from the 3'-hydroxyl terminus of a pre-existing oligodeoxynucleotide. The oligonucleotide-primed synthesis of RNA by primase occurs in both of the G4oric-specific priming system and the dnaB protein associated general priming system. This priming reaction of primase is verified by a number of biochemical methods, including inhibition by modified 3'-phosphate of oligonucleotides and deoxyribonuclease I and ribonuclease H cleavages. We also show that the primed RNA is an effective primer for the synthesis of DNA chain by E. coli DNA polymerase III holoenzyme. The significance of this finding to primases generating multimeric length RNA is discussed.     

Pulmonary vein stenosis after catheter ablation of atrial fibrillation

BACKGROUND: This report describes the complication of pulmonary vein stenosis with resultant severe pulmonary hypertension that developed in 2 patients after successful catheter ablation of chronic atrial fibrillation. METHODS AND RESULTS: Three months after successful catheter ablation of atrial fibrillation, both patients developed progressive dyspnea and pulmonary hypertension. Both were found to have severe stenosis of all 4 pulmonary veins near the junction with the left atrium. Balloon dilation of the stenotic pulmonary veins was performed in these patients, with improvement in dyspnea and pulmonary hypertension. CONCLUSIONS: The complication of pulmonary vein stenosis is potentially life-threatening, and the application of radiofrequency current within the pulmonary veins with standard catheter technology should be avoided. This complication can be treated with balloon dilation, although the long-term course is unknown.     

Interleukin-1 mediates a rapid inflammatory response after injection of adenoviral vectors into the brain

Adenovirus-mediated gene transfer into the brain is associated with significant inflammation and activation of anti-vector and anti-transgene immune responses that curtail the gene delivery of adenoviruses and therapeutic efficacy. Elucidating the molecular mediators of inflammatory and immune responses to adenoviruses injected into the brain should allow us to inhibit their inflammatory actions, thereby reducing vector clearance and enhance adenoviral-mediated gene transfer into the CNS. Cytokines are primary mediators of the immune response and are released during inflammation. Here we report for the first time that injection of replication-deficient adenovirus vectors into the cerebral ventricles of rats causes a rapid increase in body temperature. This fever response precedes any vector-encoded transgene expression and occurs with vectors encoding no transgene, as well as with vectors encoding a therapeutic transgene i.e., HSV1-thymidine kinase. No fever is detected after infection of the striatum, an important brain target in studies on neurodegeneration. After infection of the brain ventricles, CSF levels of immunoreactive tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta increase significantly (up to 300-fold). In the hypothalamus, the locus of thermoregulation in the brain, only IL-1beta and IL-6 are significantly elevated. A neutralizing TNF-alpha antibody has no effect on adenovirus-induced fever. However, pretreatment with either the IL-1 receptor antagonist or the cyclooxygenase inhibitor flurbiprofen completely abolishes adenovirus-induced fever, suggesting that IL-1 and prostaglandins are direct mediators of this response. These results are the first to demonstrate that IL-1, but not TNF-alpha, is the main mediator of a very early inflammatory response to adenovirus in the brain.     

GPRS的服务质量及其测量

(GN Nettest)　　一、GPRS简介　　通用分组无线服务 ( GPRS)系统扩展了当前世界上最流行的第二代移动系统一基于语音的 GSM的应用 ,使其能够收发基于分组的数据 ;同时保留了无线接口的基本内容 ,如时分多路复用和频率分配方案 ,以使 GPRS和 GSM能够共存于同一网络上。　　 1 .特性　　传统的 GSM拨号数据接入为用户提供了最大960 0波特的速率。GPRS能够结合多个 GSM时隙 ,在上行链路和下行链路上 ,最多可以使用八个 GSM时隙 ,提供最高 1 70 kbit/sec的带宽。此外 ,GPRS采用全新的 IP网络“一直在线”接入模式 :移动用户开…     

Spatially resolved nanoscale chemical and mechanical characterization of ZDDP antiwear films on aluminum–silicon alloys under cylinder/bore wear conditions

summary  Understanding the lubrication of aluminum–silicon (Al–Si) alloys (>18 Si) under conditions similar to those in the cylinder/bore system is vital to determining their applicability to current engine designs. A novel investigation of the location of zinc-dialkyl-dithiophosphate (ZDDPs) antiwear (AW) film formation on an Al–Si alloy has been performed using X-ray absorption near edge structure (XANES) analysis, X-ray photoelectron emission spectroscopy (X-PEEM), and imaging nanoindentation techniques. A study of the initial stages of wear (10 min) to prolonged rubbing (60 min) was performed. The findings show that the film forms primarily on the raised silicon grains and is consistent with a zinc polyphosphate glass. The film has an elastic modulus of ~70 GPa and a similar elastic response to a ZDDP AW film formed on steel under the same conditions. This provides the first direct observation and characterization of a ZDDP antiwear film on Al–Si alloys using spatially resolved chemical and mechanical techniques at the nanoscale.