MTT法评价医用骨科材料的细胞毒性

目的:评价三种常用医用骨科材料的细胞毒性。方法:通过制备表面阳极氧化钛合金(Ti-6Al-4V)材料、聚醚醚酮(PEEK)材料和β-磷酸三钙(β-TCP)材料的浸提液与L929细胞接触,进行MTT试验。结果:所有样品浸提液的细胞相对增殖率(RGR)均≥80%,细胞毒性反应分级为0至1级。结论:这三类材料的0.2g/ml浸提液均显示无明显的细胞毒性。     

一种新的以影像为基础的细胞增殖和细胞毒性检测方法

噻唑蓝3-(4,5-二甲基-2-)-2,5-二苯基溴化四唑盐(MTT)比色法是传统上检测细胞增殖和细胞毒性的常用方法.CloneSelectTM成像系统是一种以影像为基础的用于分析细胞生长的可视检测系统.本研究采用人结直肠癌HCT116细胞系,运用CloneSelect成像系统和MTT方法分别检测药物阿的平的细胞毒性,并采用Bland-Altman作图法比较两种实验方法获得的pEC50值,分析两种研究方法获得的结果的一致性.结果表明,CloneSelectTM成像系统和MTT法获得的pEC50值具有较好的一致性.与MTT方法相比,基于影像的CloneSelectTM成像分析技术检测快速、无损伤且结果更准确,获取资料不损伤细胞,允许后续其它时间点或动力学检测.研究提示,这种新的以影像为基础的检测技术可以替代MTT方法,用于分析不同药物的抗细胞增殖活性.     

硅磷酸钙复合骨水泥对L929细胞增殖相关基因表达的影响

制备了新型的硅磷酸钙复合骨水泥,Real-time PCR法研究了该材料对L929细胞3个细胞增殖相关基因表达的影响,并与MTT法做对比,旨在探讨从分子水平评价材料生物相容性的可能性及其作用机制。MTT结果表明,所有实验组浸提液对L929细胞均没有明显的毒性作用,一定浓度的含硅酸三钙骨水泥的浸提液能刺激细胞的增殖。Real-time PCR结果显示,不含硅酸三钙骨水泥不同浓度的浸提液培养3 h后,L929细胞CyclinD1、PCNA和SDH基因mRNA水平与对照组相比变化不大;添加50%wt硅酸三钙的骨水泥上述3个基因mRNA水平均显著增高。其中CyclinD1 mRNA水平在浸提液浓度为100%、75%和50%时,分别比对照组增加了44.74%、51.79%和43.84%;在浸提液浓度分别为75%、50%和100%、75%时,PCNA和SDH基因mRNA水平分别比对照组增加了64.60%、54.76%和45.07%、54.85%。结果提示,制备的这种新型硅磷酸钙复合骨水泥具有良好的生物活性,L929细胞CyclinD1、PCNA、SDH基因表达量的变化可以作为评价材料生物相容性的一种潜在方法。     

许旺细胞复合改性PLA\PGA的体外生物学研究

目的：评价小鼠许旺细胞体外复合改性聚乳酸\聚羟基乙酸（PLA\PGA）的细胞活性及生物相容性。方法：转绿色荧光蛋白基 因（GFP）小鼠的许旺细胞传代培养至第2 代,然后通过MTT 检测在不同改性技术（H2O2、NaOH、NaClO4、K2CrO4及超声波）处理 的PLA\PGA 浸提液中许旺细胞的增殖情况,检测许旺细胞在PLA\PGA表面的黏附及其细胞形态。结果：于培养1 d,3 d测得在 不同改性技术处理的PLA\PGA浸提液OD值,1 天时,各浸提液组和对照组相比无显著性差异,许旺细胞的活力及增殖无影响。3 天时,经NaClO4及K2CrO4处理的PLA\PGA 与对照组相比具有统计学差异,影响许旺细胞的增殖,对许旺细胞有毒性;荧光显微 镜下观察到许旺细胞在改性PLA\PGA 表面逐渐伸展,形成伪足,最终粘附在材料表面。结论：经H2O2、NaOH 及超声波改性 PLA\PGA无细胞毒性,具有良好的生物相容性和黏附性,可以用于组织工程化神经的构筑。     

粪便提取液毒性检测方法的建立及应用

目的建立检测人体粪便提取液对肠上皮细胞毒性的方法。方法以Caco-2细胞为体外模型,应用建立好的毒性检测方法：用MTT法（四甲基偶氮唑盐微量酶反应比色法）检测细胞毒性,用单细胞凝胶电泳技术检测遗传毒性,对糖尿患者和健康人的粪便提取液进行分析。结果糖尿病患者粪便提取液的细胞毒性显著高于健康人（n=30,P〈0.05）;其遗传毒性显著高于阴性对照PBS（P〈0.05）,与健康人相比有升高趋势,但差异无统计学意义。结论粪便提取液的毒性检测方法可以简便、有效地检测人体粪便中毒性物质对肠上皮细胞的影响,因此可作为评价肠道菌群状态的方法。     

利用草鱼CIK细胞和MTT法测定镉和铬毒性试验的优化

四噻唑蓝(MTT)比色法是由Mosmann提出后Tada和Green等人又对该方法进行了改进。MTT法是根据活细胞的线粒体脱氢酶能使四噻唑盐MTT裂解为蓝色的产物,且生成量与存活细胞数呈正比,根据颜色的深浅,用比色法进行检测。经多次改进,该方法已实现半自动化操作,其简单、经济、快速、无放射性污染,检测结果与同位素掺入法有良好的一致性,是一种可以和放射活性测定法相媲美的检测细胞毒性和细胞增殖的敏感方法。本文利用主要养殖鱼类草鱼的肾脏细胞系CIK为靶细胞,从MTT法的细胞接种浓度、MTT浓度及温育时间等几个重要参数,研究了对CIK细胞应…     

靶向IRE1a干扰质粒构建及对ERS时细胞增殖及凋亡的影响

目的构建靶向人IRE1a的shRNA干扰质粒（pSUPER-IRE1a）并观察其对人HeLa细胞和HepG2细胞增殖及凋亡的影响。方法设计并合成靶向IRE1a基因的两条shRNA,分别克隆至真核表达载体pSUPER构建重组质粒pS1、pS2,依次转染入HeLa细胞和HepG2细胞中。采用RT—PCR检测pS1、pS2转染前后IRE1a在HeLa细胞和HepG2细胞中的mRNA水平,免疫印迹检测pS1、pS2转染前后IRE1a蛋白的表达;MTT比色法、BrdU／DAPI双免疫荧光法及流式细胞仪分别检测各重组质粒对HeLa细胞和HepG2细胞增殖及凋亡的影响。结果干扰质粒（pSUPER-IRE1a）能有效抑制HeLa细胞和HepG2细胞中IRE1a基因的表达;成功转染后,细胞处于内质网应激（ER stress）状态时,各实验组细胞增殖率及凋亡率与对照组比较,差异均具有统计学意义P〈0．05）。结论成功构建靶向人IRE1a的shRNA真核表达载体pS1、pS2,有效抑制了HeLa细胞和HepG2细胞中IRE1a的表达;细胞处于ERS状态时,IRE1a-shRNA有效促进HeLa、HepG2两种肿瘤细胞的增殖;抑制HeLa和HepG2细胞的凋亡。     

新型战伤急救止血剂体外细胞毒性研究

目的:研究新型战伤急救止血剂的体外细胞毒性,初步探讨其用于战伤急救止血时的生物安全性.方法:参照我国医疗器械生物学评价标准,选用小鼠L929细胞,应用MTT法、直接接触培养法、流式细胞检测细胞凋亡法、扫描电镜直接观察细胞生长状况等检测新型战伤急救止血剂的细胞毒性.结果:新型战伤急救止血剂细胞毒性为0-1级,符合我国医疗器械评价标准毒性分级标准,各浓度组与阴性对照组无差异,P＞0.05;L929细胞与沸石直接接触生长良好,流式细胞仪检测细胞凋亡率与阴性对照组无差异;扫描电镜观察在沸石表面生长良好.结论:复合新型战伤急救止血剂细胞相容性良好,符合我国医疗器械安全性评价标准,是一种安全、高效、多功能的战伤止血剂.     

用流式细胞术评价一种新型人工肝材料的生物相容性

目的通过用流式细胞术（FCM）观察丙稀酰胺接枝改性聚丙烯膜 （PP-g-AAm）的生物相容性,来评价FCM在检测医用生物材料的生物相容性中的作用.方法：用材料浸提液培养L929细胞24 h后用FCM检测细胞增殖周期; 用改性前、后的膜材料分别与新提取的PRP（富含血小板血浆）和PBMC（末梢血单个核细胞）孵育培养后,用FCM分别检测血小板和PBMC的激活标志物CD62P、CD63和CD69.结果：PP-g-AAm 组的PI与阴性组及空白对照组比较差异无统计学意义（P=0.063,P=0.053）,而与阳性对照组比较差异有统计学意义（P=0.002）.PP-g-AAm膜组CD62P、CD63及CD69的表达率明显少于对照组（P=0.042, P=0.004,P=0.013）.结论：PP-g-AAm无细胞毒性并具有良好的生物相容性,FCM在生物材料的生物相容性评价中有着广泛的应用价值.     

下颌下腺脱细胞基质材料的生物相容性及毒理学研究

为探讨下颌下腺脱细胞基质支架材料的生物相容性,应用3%TritonX-100对SD大鼠的下颌下腺组织进行脱细胞处理,制备脱细胞基质支架材料,将该材料的浸提液注入小鼠体内进行全身急性毒性试验,观察小鼠全身反应.将该材料植入Wistar鼠肌内进行体内植入试验,不同时间观察支架材料与组织反应.用传代培养的第2代下颌下腺细胞与支架材料体外复合培养,第7 d时进行MTT检测,观察支架材料对细胞增殖的影响.全身急性毒性试验结果显示,实验组与对照组无显著性差别(P＞0.05),体内植入试验2、4、8 W时光镜下表现与对照组基本相似,MTT检测结果,细胞相对增长率为91.66%,支架材料的毒性为0级.结果可见,经3%TritonX-100脱细胞处理后所制备的下颌下腺生物衍生支架材料具有良好的生物相容性,对机体无毒害作用.     

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).