Antioxidant Effect of Human Selenium-containing Single-chain Fv in Rat Cardiac Myocytes

Reactive oxygen species（ROS） plays a key role in human heart diseases. Glutathione peroxidase（GPX） functions as an antioxidant as it catalyzes the reduction of hydroperoxide. In order to investigate the antioxidant effect of human selenium-containing single-chain Fv（Se-scFv-B3）, a new mimic of GPX, a model system of hydrogen peroxide（H202）-induced rat cardiac myocyte damage was established. The cardiac myocyte damage was characte- rized in terms of cell viability, lipid peroxidation, cell membrane integrity, and intracellular H202 level. The Se-scFv-B3 significantly reduced H2O2-induced cell damage as shown by the increase of cell viability, the decline of malondialdehyde（MDA） production, lactate dehydrogenase（LDH） release, and intracellular H2O2 level. So Se-scFv-B3 may have a great potential in the treatment of human heart diseases induced by ROS.

Novel Selenium-containing Human Single-chain Variable Fragment with Glutathione Peroxidase Activity from Computer-aided Molecular Design

In order to enhance the glutathione peroxidase（GPX） catalytic activity of the selenium-containing single-chain variable fragments（Se-scFv）, a novel human scFv was designed on the basis of the structure of human antibody and optimized via bioinformatics methods such as homologous sequence analysis, three-dimensional（3D） model building, binding-site analysis and docking. The DNA sequence of the new human scFv was synthesized and cloned into the expression vector pET22b（＋）, then the scFv protein was expressed in soluble form in Escherichia coli BL21（DE3） and purified by Ni2＋-immobilized metal affinity chromatography（IMAC）. The serine residue of scFv in the active site was converted into selenocysteine（Sec） with the chemical modification method, thus, the human Se-scFv with GPX activity was obtained. The GPX activity of the Se-scFv protein was characterized. Compared with other Se-scFv, the new human Se-scFv showed similar efficiency for catalyzing the reduction of hydrogen peroxide by glutathione. It exhibited pH and temperature dependent catalytic activity and a typical ping-pong kinetic mechanism.

Antioxidant Effect of Selenium-containing Glutathione S-Transferase in Rat Cardiomyocytes

As one of the most important antioxidant enzymes, glutathione peroxidase（GPX） protects cells and tissues from oxidative damage, and plays an important role in cardiovascular and cerebrovascular injuries induced by oxida- tive stress. The antioxidant effect of selenium-containing glutathione S-transferase（Se-GST）, a mimic of GPX was investigated on rat cardiomyocytes. To explore the protection function of Se-GST in hydrogen peroxide（H202） chal- lenged rat cardiomyocytes, we examined malondialdehyde（MDA）, lactate dehydrogenase（LDH）, superoxide dismu- tase（SOD） and cell apoptosis. The results demonstrate exposure of rat cardiomyocytes to H202 for 6 and 12 h induced the significant increases of MDA, LDH and apoptosis rate of cardiomyocytes, but pretreatment of rat cardiomyocytes with Se-GST at 0.0005 or 0.001 unit/mL prevents oxidative stress induced by H202 with the decreases of cell apopto- sis. All the results hint Se-GST has antioxidant activity for oxidative stress challenged rat cardiomyocvtes.

Imprinted Human Serum Albumin with Antioxidant Activity

In order to create a new mimic of glutathione peroxidase（GPx）, bioimprinting was used to generate gluta-thione（GSH） binding site and chemical modification was used to incorporate catalytic group selenocystine（Sec）. Human serum albumin（HSA） and S-substituted dinitrophenyl glutathione（GSH-S-DNP） were chosen as the imprinted matrix and imprinting template, respectively, to generate a GSH-imprinted protein（GSH-HSA） by bioimprinting. Sec was incorporated into the GSH-HSA by chemical modification to give a new GPx mimic（Se-GSH-HSA）. Se-GSH-HSA displayed considerably higher GPx activity than non-printed HSA（Se-HSA）. The enzymic properties and kinetics of Se-GSH-HSA were studied. Moreover, Se-GSH-HSA was confirmed to have stronger antioxidant ability to protect mitochondria against oxidative damage with ferrous sulfate/ascorbate-induced mitochondria damage model, indicating that Se-GSH-HSA has potential application in medicine.

D-二聚体和纤维蛋白原水平预测支气管动脉栓塞术治疗支气管扩张大咯血临床疗效及预后的临床价值

目的:探讨D-二聚体和纤维蛋白原水平预测支气管动脉栓塞术治疗支气管扩张大咯血的临床疗效及预后的临床价值。方法:选取50例2011年11月至2016年11月期间于我院治疗的支气管扩张大咯血患者进行研究,所有患者均进行支气管动脉栓塞术治疗,根据临床疗效评价标准结果分为总有效组(n=40)和无效组(n=10),随访1年,根据预后的复发情况分为预后好组(n=38)和预后差组(n=12),分别比较总有效组和无效组、预后好组和预后差组D-二聚体和纤维蛋白原水平,采用受试者工作特征(ROC)曲线分析D-二聚体和纤维蛋白原对支气管扩张大咯血患者的预测价值。结果:手术后总有效组和无效组患者D-二聚体、纤维蛋白原水平均高于手术前,且总有效组高于无效组(P<0.05)。手术后预后好组和预后差组患者D-二聚体、纤维蛋白原水平均高于手术前,且预后好组高于预后差组(P<0.05)。ROC曲线分析显示,D-二聚体和纤维蛋白原对支气管扩张大咯血患者均具有较高的敏感度和特异度,曲线下面积分别为0.725和0.806。结论:采用支气管动脉栓塞术治疗支气管扩张大咯血,疗效及预后比较好的患者D-二聚体和纤维蛋白原水平均较高,并且其敏感度和特异度较高,具有一定的临床预测价值。

肺癌化疗住院患者院内感染危险因素及炎症因子、T淋巴细胞亚群改变研究

目的:探讨肺癌化疗住院患者院内感染危险因素及炎症因子、T淋巴细胞亚群改变。方法:采用回顾性研究的方法,选择我院呼吸内科2015年1~2019年10月收治的肺癌化疗住院患者106例作为研究对象,根据其在院内化疗期间是否发生感染分为感染组(n=30)和非感染组(n=76)。对感染组患者病原分布及两组患者炎性因子C反应蛋白(CRP)、降钙素原(PCT)和白介素6(IL-6)水平及外周血CD4+T淋巴细胞、CD8+T淋巴细胞、CD4/CD8比值水平进行比较,探讨其发生的危险因素。结果:30例患者共检出病原35例,其中革兰氏阳性菌25例,占71.43%,革兰氏阳性菌9例,占25.71%;感染组CD4+T淋巴细胞、CD4/CD8水平显著低于非感染组患者,CD8+T淋巴细胞水平显著高于非感染组患者;感染组CRP、PCT、IL-6水平显著高于非感染组患者;单因素分析及多元Logistic分析结果表明,肿瘤分期III^IV期、入院时CD4/CD8、CRP、PCT、IL-6水平是肺癌化疗住院患者医院感染的独立危险因素。结论:除患者临床特征外,入院时炎性因子及T淋巴细胞水平也是肺癌化疗住院患者发生医院感染的危险因素,应加强对高危人群的病原培养及重点监控,尽早采取防控措施。