Dielectric screening effect of electronic polarization and intramolecular hydrogen bonding

Recent site‐resolved hydrogen exchange measurements have uncovered significant discrepancies between simulations and experimental data during protein folding, including the excessive intramolecular hydrogen bonds in simulations. This finding indicates a possibility that intramolecular charge–charge interactions have not included sufficient dielectric screening effect of the electronic polarization. Scaling down peptide atomic charges according to the optical dielectric constant is tested in this study. As a result, the number of intramolecular hydrogen bonds is lower than using unscaled atomic charges while reaching the same levels of helical contents or β‐hairpin backbone hydrogen bonds, because van der Waals interactions contribute substantially to peptide folding in water. Reducing intramolecular charge–charge interactions and hydrogen bonding increases conformational search efficiency. In particular, it reduces the equilibrium helical content in simulations using AMBER force field and the energy barrier in folding simulations using CHARMM force field.     

Cytokine mRNA expression in unilateral ischemic-reperfused rat lung with salt solution supplemented with low-endotoxin or standard bovine serum albumin

Our aim was to determine whether cytokine mRNA expression is induced by experimental manipulation including artificial perfusate or ischemia-reperfusion (I/R) in an isolated, perfused rat lung model. Constant pulmonary flow [Krebs-Henseleit solution supplemented with low-endotoxin (LE) or standard (ST) bovine serum albumin 4%, 0.04 ml/g body wt] and ventilation were maintained throughout. Right and left pulmonary arteries were isolated, and the left pulmonary artery was occluded for 60 min and then reperfused for 30 min. Analysis of tumor necrosis factor-alpha, IL-1 beta, IL-6, IL-10, and IFN-gamma mRNA expression by RT-PCR and evaluation of vascular permeability by bronchoalveolar lavage (BAL) fluid albumin content were conducted separately in right and left lung. Both LE and ST groups (each 12 rats) showed increases in vascular permeability by I/R (BAL fluid albumin content: 5.53 +/- 1.55 vs. 15.63 +/- 8.87 and 4.76 +/- 2.71 vs. 16.72 +/- 4.85 mg.ml BAL fluid-1.g lung dry wt-1, mean +/- SD; right vs. left lung in LE and ST groups, P < 0.05 between right and left). Cytokine mRNA expression was significantly higher in the I/R lung than in the control lung in the LE group, whereas it was higher in the control lung in the ST group (P < 0.05). mRNAs of not only proinflammatory but also anti-inflammatory cytokines were expressed in I/R lung, which are expected to aggravate I/R injury. The reversed pattern of cytokine mRNA expression in the ST group was possibly due to the longer perfusion of control lung with perfusate containing endotoxin, which caused no lung damage without I/R.     

混合盐碱胁迫对青山杨渗透调节物质及活性氧代谢的影响

为研究青山杨(Populus pseudo-cathayana × P. deltoides)对盐碱的适应能力,对青山杨2年生扦插苗进行不同盐度和碱度的28组胁迫处理.结果表明：随盐浓度增加,青山杨叶片的电解质外渗率、丙二醛和脯氨酸含量呈上升趋势,可溶性糖、SOD和POD活性先升后降.pH值升高使电解质外渗率、丙二醛和POD活性呈上升趋势,脯氨酸和可溶性糖含量先升后降,SOD活性上升趋势不明显.盐浓度低于100 mmol·L^-1时,随pH值升高,各项生理指标的变化不明显,SOD具有较高的活性;盐浓度在200 mmol·L^-1、pH 8.99以上时,其电解质外渗率在50%以上,POD活性和丙二醛含量大幅度增加,脯氨酸和可溶性糖含量下降,SOD活性较低.推断盐浓度>200 mmol·L^-1、pH>8.99的盐碱条件不适宜青山杨的生长.     

生物医学信息资源的整合和导航系统的建立

生物医学信息资源的大量涌现,带来了一些问题。为了节约读者检索时问,提高查全率、查准率。我们有必要利用现有的技术条件对大量有用的生物医学数据库进行收集、整合、加工,形成具有实用性、系统性的新的有机整体。针对各类数据库建立生物医学信息的导航系统。两者的结合可以有效、系统地满足医务人员和科研人员对信息的需求。     

The use of next generation sequencing technology to study the effect of radiation therapy on mitochondrial DNA mutation

The human mitochondrial genome has an exclusively maternal mode of inheritance. Mitochondrial DNA (mtDNA) is particularly vulnerable to environmental insults due in part to an underdeveloped DNA repair system, limited to base excision and homologous recombination repair. Radiation exposure to the ovaries may cause mtDNA mutations in oocytes, which may in turn be transmitted to offspring. We hypothesized that the children of female cancer survivors who received radiation therapy may have an increased rate of mtDNA heteroplasmy mutations, which conceivably could increase their risk of developing cancer and other diseases. We evaluated 44 DNA blood samples from 17 Danish and 1 Finnish families (18 mothers and 26 children). All mothers had been treated for cancer as children and radiation doses to their ovaries were determined based on medical records and computational models. DNA samples were sequenced for the entire mitochondrial genome using the Illumina GAII system. Mother's age at sample collection was positively correlated with mtDNA heteroplasmy mutations. There was evidence of heteroplasmy inheritance in that 9 of the 18 families had at least one child who inherited at least one heteroplasmy site from his or her mother. No significant difference in single nucleotide polymorphisms between mother and offspring, however, was observed. Radiation therapy dose to ovaries also was not significantly associated with the heteroplasmy mutation rate among mothers and children. No evidence was found that radiotherapy for pediatric cancer is associated with the mitochondrial genome mutation rate in female cancer survivors and their children.     

Supreme™ laryngeal mask airway use in general Anesthesia for category 2 and 3 Cesarean delivery: a prospective cohort study

Background

The Supreme? laryngeal mask airway (SLMA) is a single-use LMA with double lumen design that allows separation of the respiratory and the alimentary tract, hence potentially reducing the gastric volume and risk of aspiration. The purpose of this prospective cohort study is to evaluate the the role of the SLMA as an airway technique for women undergoing category 2 and 3 Cesarean delivery under general anesthesia.

Methods

We recruited 584 parturients who underwent category 2 or 3 Cesarean delivery under general anesthesia, in which 193 parturients underwent category 2 and 391 parturients underwent category 3 Cesarean delivery. The primary outcome was insertion success rate at 1st attempt in SLMA insertion. The secondary outcomes included anaesthetic, obstetric outcomes and maternal side effects associated with airway device.

Results

The 1st attempt insertion success rate was 98.3%, while the overall insertion success rate was 100%. The mean (Standard deviation) time to effective ventilation was 15.6 (4.4) seconds. Orogastric tube insertion was successful at the 1st attempt in all parturients. There was no clinical evidence of aspiration or regurgitation. No episodes of hypoxemia, laryngospasm or bronchospasm were observed intra-operatively. The incidence of complications was low and with good maternal satisfaction reported.

Conclusions

The SLMA could be an alternative effective airway in category 2 and 3 parturients emergency Cesarean Delivery under general anesthesia in a carefully-selected obstetric population.

Trial registration

Clinical Trials Registration: Clinicaltrials.gov Registration NCT02026882. Registered on December 31, 2013.

     

脱落酸诱导气孔关闭的信号转导研究

气孔保卫细胞是单个细胞水平研究ABA信号转导机制的一个模式系统。脱落酸(ABA)通过对保卫细胞生理生化状态、胞质Ca^2 浓度及其离子通道调节诱导气孔关闭过程。这个过程涉及的因素有：ROS、IP3、cADPR、蛋白质的可逆磷酸化等。     

黄芩甙对铜绿假单胞菌R质粒的消除作用

测定黄芩甙对铜绿假单胞菌R质粒的消除作用 ;以携带R质粒的铜绿假单胞菌株PA16为靶细菌 ,以黄芩甙作为R质粒消除剂 ,进行R质粒体内外消除试验 ;体外消除实验结果表明 ,黄芩甙对PA16的消除率为 5 .1% ,明显高于空白对照组 ,也高于EB对照组的结果 ;体内R质粒消除率为 12 .0 % ,明显高于对照组 ;黄芩甙在体内外对铜绿假单胞菌R质粒具有较强的消除作用 ,为其实际应用提供实验依据。     

蛋白酪氨酸磷酸酶SHP-2在乳腺癌细胞移动及粘附中的作用

探讨蛋白酪氨酸磷酸酶SHP 2在乳腺癌细胞MCF 7的移动及粘附中的作用 .利用基因重组技术分别将野生型SHP 2与突变型SHP 2与绿色荧光蛋白GFP的基因片段构成重组质粒 (SHP 2 GFP、SHP 2C >S GFP) .脂质体转染法分别转入MCF 7中 ,表达成功后筛选并建立SHP 2 GFP和SHP 2C >S GFP细胞株 .荧光显微镜观察细胞移动情况 ,免疫印迹法检测粘附分子E 钙粘蛋白和金属蛋白酶MMP 1及MMP 9的表达 .实验后建立SHP 2 GFP及SHP 2C >S GFP细胞株 ,同时观察到SHP 2C >S GFP细胞的形态发生明显改变 :从梭形状态变成圆形状态 .荧光显微镜发现 ,MCF 7细胞和SHP 2 GFP、SHP 2C >S GFP转染的细胞在 3h、6h、9h的移动情况分别是MCF 7为 10 %、2 3%、5 4% ,SHP 2 GFP为 15 %、4 9%、98% ,SHP 2C >S GFP为 4 %、11%、30 % .免疫印迹结果表明 ,SHP 2C >S GFP细胞的E 钙粘蛋白表达比SHP 2 GFP细胞明显升高 (P <0 0 5 ) .MMP 1及MMP 9的表达量在SHP 2 GFP细胞中有所增强 (P <0 0 5 ) .实验表明 ,SHP 2可能通过调节粘附分子和基质金属磷酸酶而在细胞移动、粘附中发挥重要作用