超氧阴离子自由基对大鼠脑皮层神经细胞的损伤作用

为了探讨超氧阴离子自由基对神经细胞的影响,以产生超氧阴离子自由基系统（XO/X）作用于原代培养的新生大鼠大脑皮层神经元,分析神经细胞的生长状态、蛋白质被氧化修饰的程度、脂质过氧化程度、核DNA损伤程度、亚细胞结构变化以及Cu/ZnSOD基因表达等变化。结果显示：超氧阴离子自由基可使神经细胞的生长状态不佳,ATP酶活性降低为4.223μmol/(mg.min^-1)(Pr)。细胞总羰基含量增加为295.40μmol/g湿重,LPO含量增加为4.87mol/g(Pr),膜脂流动性下降（P值为0.398),核DNA单链断裂增加（DNA在SCG中的迁移率为7.35mm),亚细胞结构变化（线粒体肿胀和变性等）以及SOD基因表达增强（SOD含量、SOD活性和SODmRNA丰度均增加）。结果说明超氧阴离子自由基可损伤神经细胞的蛋白质、核酸、脂质和亚细胞结构。     

植物超氧化物歧化酶（SOD）的研究进展

超氧化物歧化酶(superoxide dismutase,SOD)在需氧原核生物和真核生物中广泛存在,是活性氧清除系统中第一个发挥作用的抗氧化酶。植物正常代谢过程和在各种环境胁迫下均能产生活性氧和自由基,活性氧和自由基的积累引起细胞结构和功能的破坏。SOD岐化超氧物阴离子自由基生成过氧化氢和分子氧,在保护细胞免受氧化损伤过程中具有十分重要的作用。本文综述了SOD的功能、在细胞中的分布、表达调控和与植物抗逆性的关系。 Abstract:Superoxide Dismutases (SODs) are ubiquitously expressed antioxidant enzyme in aerobic organisms and catalyze dismutation of superoxide anion to hydrogen and molecular oxygen,the first step in active oxygen-scavenging systems.SODs play a central role in protecting cells against the toxic effects of reactive oxygen species generated during normal cellular metabolic activity or as a result of various environmental stresses.This paper reviews the expression and regulation of Sod genes and their functional role(s) during development and in response to stresses.     

超氧化物岐化酶在医学领域的研究现状

超氧化物歧化酶(SOD)是生物体内清除超氧阴离子自由基(O2-.)的一种重要金属酶,具有重要的生理功能,在医药、食品等方面有广泛的应用前景,是目前医学、分子生物学领域研究的热点之一。现对SOD的分类、分布、结构、性质、在相关疾病中的研究进展、临床应用等方面做一综述。     

红果参多糖的提取纯化及抗氧化活性研究

利用超声波辅助水提醇沉法提取并纯化红果参多糖.以抗坏血酸(VC)作参照物,考察了红果参多糖对羟基自由基、超氧阴离子自由基、亚硝基的清除效果及对油脂的抗氧化性能.结果表明:红果参多糖能很好的清除羟基自由基和超氧阴离子自由基,其清除能力与多糖浓度呈正相关性,对油脂的氧化有明显的抑制作用,对亚硝基的清除效果不明显.     

两株乳酸杆菌SY13和LJJ对活性氧的耐受性

【目的】从传统发酵乳制品中筛选具有抗氧化能力的乳酸菌菌株并对其抗氧化特性进行评价。【方法】分别利用乳酸杆菌SY13和LJJ完整细胞和无细胞提取物对亚油酸过氧化的抑制效果,对DPPH自由基、羟自由基、超氧阴离子自由基清除能力,对过氧化氢的耐受性以及对亚铁离子的螯合能力和还原活性进行了研究。【结果】结果表明,SY13和LJJ对亚油酸过氧化的最大抑制率分别达到了62.95%和66.16%;两菌株的无细胞提取物清除超氧阴离子和羟自由基的的效果较好,LJJ完整细胞对超氧阴离子和羟自由基没有清除能力;SY13和LJJ对DPPH自由基的清除能力及对亚铁离子的螯合能力都是完整细胞优于无细胞提取物,还原活性分别相当于305 μmol/L和294 μmol/L的L-cysteine。【结论】以上指标测定的结果说明,这两株乳酸杆菌具有较好的抗氧化能力,具有潜在的应用价值。     

灵芝液体发酵清除自由基活性产物发酵条件的优化

以红灵芝(Ganoderma.lucidum)为实验菌株,对其液体发酵活性产物清除自由基的发酵条件进行了研究。实验考察了培养基成分对灵芝液体发酵所产生的有效产物清除自由基能力的影响。结果表明,葡萄糖、酵母粉分别为灵芝发酵活性产物清除自由基效果较合适的碳源、氮源,最佳质量浓度分别为40 g.L-1和3 g.L-1,清除自由基的能力分别为55.7%、40.8%和66.5%、50.6%;铁离子对灵芝发酵产物清除超氧阴离子具有明显的效果,适宜质量分数为70×10-6;清除超氧阴离子的能力为54.6%,而硒离子对灵芝发酵产物抑制羟自由基有明显的促进作用,最适的质量分数为90×10-6清除羟自由基的能力为67.7%。油酸能促进灵芝发酵产物的清除超氧阴离子和羟自由基的能力,适宜的质量分数为0.1%,清除两种自由基的能力分别为:73.7%,53%。     

资木瓜总黄酮的体内外抗氧化活性研究

采用70%乙醇回流提取,大孔吸附树脂纯化得到资木瓜总黄酮,进一步研究其体内外抗氧化活性。检测资木瓜对Fe3+的还原力,分析资木瓜对羟自由基、DPPH·自由基以及超氧阴离子自由基的清除能力,检测对LPS诱导的氧化应激小鼠模型血液中SOD和MDA的影响。结果发现资木瓜总黄酮具有良好的还原能力,对·OH和DPPH·自由基的最大清除率分别是97.8%、69.8%,但对超氧阴离子的清除率较低仅为38.3%;在体内实验中资木瓜能增加小鼠血清中SOD活性、降低MDA浓度。说明资木瓜总黄酮通过直接清除自由基、增加机体抗氧化酶SOD的活性、减少脂质过氧化物的生成,产生抗氧化活性。     

黄伞胞外多糖抗自由基作用的研究

目的:以乙醇沉淀的黄伞发酵浓缩液得到的胞外多糖为研究对象,检验其对自由基的清除作用。方法:采用电子顺磁共振(EPR)波谱仪检测黄伞胞外多糖清除羟自由基OH.和超氧阴离子自由基O2-.的作用。结果:在样品浓度均为100mg/mL的条件下,利用Fenton反应体系,黄伞胞外多糖对羟自由基OH.的清除率仅为38.5%;而利用次黄嘌呤-黄嘌呤氧化酶体系,黄伞胞外多糖对超氧阴离子自由基O2-.的清除率可达到80.6%。结论:黄伞胞外多糖在体外对自由基有一定的清除作用且其对超氧阴离子自由基O2-.的清除作用明显优于对羟自由基OH.的清除作用。     

牛奶子树不同部位多糖抗氧化活性比较研究

从牛奶子(Elaeagnus umbellata Thunb.)的叶片、枝条、种子中提取多糖,并研究其抗氧化活性.采用热水提取、Savage法除蛋白、80％乙醇沉淀得其粗多糖.以Vc为对照,用番红花红光度法测定其对羟基自由基的清除作用;用邻苯三酚自氧化法测定其对超氧阴离子的清除作用;用Fe3+还原力法测定其还原能力.结果表明:3个部位所含多糖对羟基自由基、超氧阴离子自由基都可起到有效的清除或抑制作用,其中对羟基自由基清除活性依次为:种子＞叶片＞枝条＞Vc,对超氧阴离子自由基清除活性依次为:种子＞Vc＞叶片＞枝条,3个部位所含多糖都有还原性,但效果都不如硫脲.     

超氧阴离子的产生及其在植物体内作用的研究

超氧阴离子自由基不仅是生物体内重要的自由基之一,也是所有活性氧自由基的前体。近年来许多文献报道生物体的一些重大疾病与超氧阴离子自由基关系密切,因此对超氧阴离子的研究具有非常重要的意义。本文综述了有关超氧阴离子自由基在生物体内及体外的产生、超氧阴离子对生物体的作用、超氧阴离子的检测方法、重点总结了超氧阴离子的产生及其在植物体内的作用。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.