Altered translesion synthesis in E. coli Pol V mutants selected for increased recombination inhibition

Replication of damaged DNA, also termed as translesion synthesis (TLS), involves specialized DNA polymerases that bypass DNA lesions. In Escherichia coli, although TLS can involve one or a combination of DNA polymerases depending on the nature of the lesion, it generally requires the Pol V DNA polymerase (formed by two SOS proteins, UmuD' and UmuC) and the RecA protein. In addition to being an essential component of translesion DNA synthesis, Pol V is also an antagonist of RecA-mediated recombination. We have recently isolated umuD' and umuC mutants on the basis of their increased capacity to inhibit homologous recombination. Despite the capacity of these mutants to form a Pol V complex and to interact with the RecA polymer, most of them exhibit a defect in TLS. Here, we further characterize the TLS activity of these Pol V mutants in vivo by measuring the extent of error-free and mutagenic bypass at a single (6-4)TT lesion located in double stranded plasmid DNA. TLS is markedly decreased in most Pol V mutants that we analyzed (8/9) with the exception of one UmuC mutant (F287L) that exhibits wild-type bypass activity. Somewhat unexpectedly, Pol V mutants that are partially deficient in TLS are more severely affected in mutagenic bypass compared to error-free synthesis. The defect in bypass activity of the Pol V mutant polymerases is discussed in light of the location of the respective mutations in the 3D structure of UmuD' and the DinB/UmuC homologous protein Dpo4 of Sulfolobus solfataricus.     

广西溢油海域的浮游植物跟踪监测与比对分析

针对广西涠洲岛海域的突发溢油事件,于2008年9月下旬进行了溢油海域浮游植物跟踪监测,并与历史资料比对,探讨溢油对浮游植物群落的影响。调查中,共记录4门106种,硅藻92种,甲藻12种,蓝藻1种,着色鞭毛藻1种,主要优势种为旋链角毛藻(Chaetoceros curvisetus)、菱形海线藻(Thalassionema nitzschioides)和洛氏角毛藻(Chaetoceros lorenzianus)。浮游植物种类多,站间差异小,分布均匀。浮游植物细胞密度高,平均2 645.32×10⁴cells·m^-3,密集中心位于涠洲岛西北部海域。优势种密度分布与浮游植物细胞密度分布态势基本一致。多样性指数(H')和均匀度(J')均较高,群落结构稳定。与国家海洋局同期调查资料及相关文献报道比对,表明溢油海域浮游植物种类组成无较大变化,细胞密度有较小降幅,密集中心不同,优势种变更明显,群落结构稳定,应重视溢油应急反应的迫切性。     

Uptake of EDTA-complexed Pb, Cd and Fe by solution- and sand-cultured Brassica juncea

Direct plant uptake of metals bound to chelating agents has important implications for metal uptake and the free-ion activity model. Uptake of hydrophilic solutes such as metal–EDTA complexes is believed to occur via bypass apoplastic flow, but many questions remain about the relative importance and selectivity of this pathway. In this study, Brassica juncea (Indian mustard) plants grown in solution- and sand-culture conditions were exposed to metal–EDTA complexes and to PTS, a hydrophilic fluorescent dye previously used as a tracer of apoplastic flow. The results suggest that there are two general phases of solute uptake. Under normal conditions, xylem sap solute concentrations are relatively low (i.e., <0.5% of concentration in solution) and there is a high degree of selectivity among different solutes, while under conditions of stress, xylem sap concentrations are significantly higher (i.e., >3% of concentration in solution) and the selectivity among solutes is less. In healthy plants, xylem sap metal–EDTA concentrations were generally an order of magnitude higher than those of PTS and differences among complexes were observed, with CdEDTA²⁻ exhibiting slightly higher xylem sap concentrations than PbEDTA²⁻ or FeEDTA⁻. Metal–EDTA complexes were found to dominate xylem sap metal speciation and the fraction of metal in xylem sap present as metal–EDTA was greater for non-nutrient metals (Pb, Cd) than for the nutrient metal Fe. Despite differences in root morphology between plants grown under solution- and sand-culture conditions, uptake of solutes was similar under both sets of growth conditions.     

Canadians' Representation of Chemical,Biological, Radiological,Nuclear, and Explosive (CBRNE) Terrorism: A Content Analysis

The global threat of terrorism raises questions about preparedness and risk communication in the context of public health and security. Although experts discriminate between chemical, biological, radiological, nuclear, and explosive (CNRNE) terrorist events, little is known about how the Canadian public represents these forms of terrorism. A stratified random sample of 1502 Canadians participated in a telephone survey on CBRNE terrorism. A word association technique was used to assess first words or images that came to mind while thinking about different types of terrorist scenarios. Content analysis of this data revealed a number of potential uncertainties and misconceptions regarding different types of terrorism scenarios. Despite most frequently providing agents in response questions surrounding chemical or biological terrorism, respondents frequently confounded agents of biological and chemical nature. Similarly, different aspects of nuclear events were not consistently distinguished. Most notably, however, a sizable proportion of respondents had difficulty providing word associations to the different types of terrorist events or only provided vague responses that closely mirrored the scenario in question. Finally, images regarding the potential impacts of scenarios were infrequent. Implications for risk communication and preparedness are discussed; in particular, the need to provide the public with more detailed information regarding the nature of different forms of CBRNE terrorism and how to best prepare for a potential event.     

糖尿病低血糖昏迷急诊救治的临床效果

目的探讨糖尿病低血糖昏迷患者采用急诊系统干预方案实施救治的临床效果。方法对我院收治的糖尿病低血糖昏迷患者120例,按随机分组方案分为对照组和观察组,每组60例。对照组采用常规急诊干预方案进行救治,观察组采用急诊系统干预方案进行救治,比较两组糖尿病低血糖昏迷患者的急诊救治效果、救治后苏醒时间和治疗总时间、急诊救治期间不良事件发生情况。结果观察组糖尿病低血糖昏迷的急诊救治总有效率达91.7%,高于对照组的71.7%,组间比较差异有显著统计学意义(P0.05);救治后苏醒时间和治疗总时间比较,观察组均短于对照组,差异均具统计学意义(P0.05);观察组急诊救治期间发生不良事件1例,对照组发生不良事件8例,差异亦有统计学意义(P0.05)。结论糖尿病低血糖昏迷患者采用急诊系统干预方案实施救治,能促使患者短时间内苏醒,维持血糖稳定,改善患者预后。     

Prognostic value of PCT,copeptin, MR-proADM,MR-proANP and CT-proET-1 for severe acute dyspnea in the emergency department: the BIODINER study

Context: Acute dyspnea is a frequent complaint in patients attending the emergency department (ED).

Objective: To evaluate the accuracy of PCT, MR-proANP, MR-proADM, copeptin and CT-proET1 for the risk-stratification of severe acute dyspnea patients presenting to the ED.

Methods: Multicenter prospective study in adult patients with a chief complaint of acute dyspnea. Pro-hormone type biomarkers concentrations were measured on arrival. Combined primary endpoint was a poor outcome.

Results: Three hundred and ninety-four patients were included, 137 (35%) met the primary endpoint. MR-proADM was the only biomarker associated with the primary endpoint (odds ratio 1.43 [95%CI: 1.13–1.82], p?=?0.003) as were the presence of paradoxical abdominal breathing (odds ratio 2.48 [95%CI: 1.31–4.68]) or cyanosis (odds ratio 3.18 [1.46–6.89])

Conclusions: In patients with severe acute dyspnea in the ED, pro-hormone type biomarkers measurements have a low added value to clinical signs for the prediction of poor outcome.     

The potential of optimizing prehospital triage of patients with suspected acute myocardial infarction using high-sensitivity cardiac troponin T and copeptin

Purpose: In patients with a suspected acute myocardial infarction (AMI), to evaluate the potential for early triage based on measurement of high-sensitivity cardiac troponin T (hs-cTnT) and copeptin in blood samples collected in the prehospital phase.

Materials and methods: In this retrospective study, we measured hs-cTnT and copeptin in blood samples collected in the ambulance form 962 patients with suspected AMI. The diagnostic accuracy was estimated by receiver-operating characteristic (ROC) curve area under the curve (AUC) for both biomarkers and a combined model. Multivariable Cox regression modelling was used to estimate the predictive value of both biomarkers.

Results: In total, 178 (19%) cases had AMI. The AUC for hs-cTnT was 0.81. Adding copeptin increased the AUC to 0.85 (p?=?0.004) and the combined model allowed a prehospital rule-out of 45% of cases without AMI (negative predictive value, NPV 98%). Both biomarkers are highly predictive of outcome.

Conclusions: A future application of hs-cTnT and copeptin measurement, performed already in the prehospital phase, could potentially improve the prehospital diagnostic and prognostic classification of patients with a suspected AMI.     

复杂型Stanford B型主动脉夹层腔内修复术中左锁骨下动脉重建方式分析

目的:总结复杂型Stanford B型主动脉夹层中左锁骨下动脉重建的经验和方法。方法:2010年4月至2016年5月,共有43例复杂型Stanford B型主动脉夹层采用腔内修复术治疗,并均重建左锁骨下动脉,其中右腋动脉-左腋动脉人工血管旁路18例,开窗技术14例,烟囱技术11例。结果:均成功手术,无术中死亡,术后造影显示支架敷贴良好,定位准确,左锁骨下动脉血流通畅。术后无头晕症状,双上肢血压差均在15 mmHg之内。1例术后5天并发逆行性A型夹层猝死。肾功能衰竭2例,行透析治疗后治愈。随访38例,失访4例,随访时间2~33月(17.0士5.2月),1例患者术后45天猝死;术后3月、1年复查主动脉CTA均示支架无移位。1例I型内漏,术后8月复查CTA示内漏消失;1例术后9月人工血管内血栓形成,中段狭窄约40%;2例并发支架远端动脉瘤形成。结论:腋动脉人工血管旁路术、开窗技术、烟囱技术进行左锁骨下动脉重建,联合主动脉腔内修复术治疗复杂型Standford B型主动脉夹层,可以取得满意的临床效果。     

应用不同统计方法预报棉铃虫发生量

运用判别分析法和逐步回归分析法,对１９８７～１９９７年棉铃虫历史资料进行研究分析,分别建立了棉铃虫３代卵发生量的判别函数式和多元回归预测式。其中,降雨量（Ｘ_３）是棉铃虫发生量多少的关键因子,经统计测验和复相关分析,均呈极显著水平。同时,分析比较了两种统计方法的优缺点以及在测报上的应用价值。     

Decisional procalcitonin thresholds are not adapted toelderly patients admitted to the emergency room

Context: Diagnosis of sepsis in elderly is challenging.

Objectives: We investigated whether procalcitonin concentrations in elderly differed from values for the general population.

Methods: Procalcitonin measurement was assessed prospectively in 307 apyretic patients ≥75 years visiting the emergency department.

Results: Median age was 86 years [IQR81–90] and 222 (72%) were female. Procalcitonin concentration was 0.057 µg/L [0.040–0.092]; 99th percentile was 0.661 µg/L. Patients with procalcitonin concentrations above decisional thresholds had lower glomerular filtration rate and higher C-reactive protein concentrations. Conclusions: Baseline procalcitonin levels are increased in elderly. Elevated values are common and associated to low-grade inflammation and lower eGFR.