不同纤维桩表面处理方式对牙根修复后抗折裂强度的影响

目的:探讨不同纤维桩表面处理方式对牙根修复后抗折裂强度的影响。方法:收集行正畸拔除的前磨牙120颗作为本研究样本,随机将120个纤维桩分为对照组、喷砂组和过氧化氢酸蚀组,每组40例。对照组纤维桩表明不给予任何处理,喷砂组给予氧化铝砂粒持续喷砂粗化处理,过氧化氢酸蚀组给予10%过氧化氢溶液处理,均包埋于纤维桩道预备好的离体牙内,采用相同树脂制备成核,行全冠修复与黏固,再模拟口腔内部环境给予样本牙冷热循环处理,经相同环境加载后,置于电子万能实验机获取样本牙抗折裂强度数据。对比三组离体牙样本体型数据、离体牙断裂方式、抗折裂强度,对三组进行为期24个月的定期随访,统计三组修复体断裂率,并采用Kaplan-Meier曲线和Log Rank法分析三组的生存状况。结果:三组的离体牙样本关于牙齿长度、牙根长度、颈部颊舌径及颈部近远中径对比差异无统计学意义(P0.05);喷砂组和过氧化氢酸蚀组的离体牙抗折裂强度显著强于对照组(P0.05);喷砂组和过氧化氢酸蚀组的牙齿折裂总发生率分别为20.00%和22.50%,均显著低于对照组的70.00%(P0.05)。但两组间比较差异无统计学意义(P0.05)。喷砂组、过氧化氢酸蚀组的生存状况显著优于对照组。结论:前磨牙修复过程中,对纤维桩表面进行喷砂或过氧化氢酸蚀处理均能提高牙根修复后抗折裂强度,改善修复体修复效果生存状况,且两种纤维桩表面处理方式对离体牙样本的断裂方式和抗折裂强度影响相当。     

Impact of single nucleotide polymorphisms in the OGG1 and XRCC1 genes on modulation of DNA damage in pesticide-exposed agricultural workers in Punjab,North-West India

Abstract

Pesticide-induced DNA damage is primarily repaired by base excision repair (BER) pathway. However, polymorphism in DNA repair genes may modulate individual’s DNA repair capacity (DRC) leading to increased genotoxicity and adverse health effects. Our first study in North-West Indian population aimed to evaluate the impact of OGG1 rs1052133 (Ser326Cys; C1245G), XRCC1 rs1799782 (Arg194Trp; C26304T) and XRCC1 rs25487 (Arg399Gln; G28152A) polymorphisms on the modulation of pesticide-induced DNA damage in a total of 450 subjects (225 pesticide-exposed agricultural workers and 225 age- and sex-matched controls). DNA damage was estimated by alkaline comet assay using silver-staining method. Genotyping was carried out by PCR-RFLP using site-specific restriction enzymes. Mann-Whitney U-test revealed elevation in DNA damage parameters (p?<?0.01) in pesticide-exposed agricultural workers than controls. Chi-square test showed significant (p?<?0.05) differences in the XRCC1 Arg194Trp (C26304T) and Arg399Gln (G28152A) genotypes among two groups. Multivariate logistic-regression analysis revealed that heterozygous genotypes of OGG1 rs1052133 (326Ser/Cys; 1245CA), XRCC1 rs1799782 (194Arg/Trp; 26304CT) and XRCC1 rs25487 (399Arg/Gln; 2815GA) were positively associated (p?<?0.05) with elevated DNA damage parameters in pesticide-exposed agricultural workers. Our results strongly indicate significant positive association of variant OGG1 and XRCC1 genotypes with reduced DRC and higher pesticide-induced DNA damage in North-West Indian agricultural workers.     

Base excision repair but not DNA double‐strand break repair is impaired in aged human adipose‐derived stem cells

The decline in DNA repair capacity contributes to the age‐associated decrease in genome integrity in somatic cells of different species. However, due to the lack of clinical samples and appropriate tools for studying DNA repair, whether and how age‐associated changes in DNA repair result in a loss of genome integrity of human adult stem cells remains incompletely characterized. Here, we isolated 20 eyelid adipose‐derived stem cell (ADSC) lines from healthy individuals (young: 10 donors with ages ranging 17–25 years; old: 10 donors with ages ranging 50–59 years). Using these cell lines, we systematically compared the efficiency of base excision repair (BER) and two DNA double‐strand break (DSB) repair pathways—nonhomologous end joining (NHEJ) and homologous recombination (HR)—between the young and old groups. Surprisingly, we found that the efficiency of BER but not NHEJ or HR is impaired in aged human ADSCs, which is in contrast to previous findings that DSB repair declines with age in human fibroblasts. We also demonstrated that BER efficiency is negatively associated with tail moment, which reflects a loss of genome integrity in human ADSCs. Mechanistic studies indicated that at the protein level XRCC1, but not other BER factors, exhibited age‐associated decline. Overexpression of XRCC1 reversed the decline of BER efficiency and genome integrity, indicating that XRCC1 is a potential therapeutic target for stabilizing genomes in aged ADSCs.     

RS‐1 enhances CRISPR‐mediated targeted knock‐in in bovine embryos

Targeted knock‐in (KI) can be achieved in embryos by clustered regularly interspaced short palindromic repeats (CRISPR)‐assisted homology directed repair (HDR). However, HDR efficiency is constrained by the competition of nonhomologous end joining. The objective of this study was to explore whether CRISPR‐assisted targeted KI rates can be improved in bovine embryos by exposure to the HDR enhancer RS‐1. In vitro produced zygotes were injected with CRISPR components (300 ng/µl Cas9 messenger RNA and 100 ng/µl single guide RNA against a noncoding region) and a single‐stranded DNA (ssDNA) repair template (100 ng/µl). ssDNA template contained a 6 bp XbaI site insert, allowing targeted KI detection by restriction analysis, flanked by 50 bp homology arms. Following microinjection, zygotes were exposed to 0, 3.75, or 7.5 µM RS‐1 for 24 hr. No differences were noted between groups in terms of development or genome edition rates. However, targeted KI rates were doubled in the group exposed to 7.5 µM RS‐1 compared to the others (52.8% vs. 25% and 23.1%, for 7.5, 0, and 3.75 µM, respectively). In conclusion, transient exposure to 7.5 µM RS‐1 enhances targeted KI rates resulting in approximately half of the embryos containing the intended mutation, hence allowing direct KI generation in embryos.     

间充质干细胞治疗新型冠状病毒肺炎研究进展及相关临床试验难点

当前新型冠状病毒肆虐,全球确诊患者超过3 500万例,累计死亡患者超过50万例,对于突发疫情,临床尚缺乏有效特异性治疗,新型冠状病毒已成为危害人类健康、社会发展的主要公共卫生问题。间充质干细胞具有抗炎和免疫调节功能,可降低重症患者体内由冠状病毒引发的细胞因子风暴,改善患者肺部纤维化,促进损伤肺组织修复,有望降低新冠肺炎的死亡率。目前已开展多项间充质干细胞治疗新型冠状病毒肺炎临床试验,初步证实了间充质干细胞应用在新冠肺炎方面的安全及有效性。在间充质干细胞治疗新冠肺炎取得进展的同期,还应看到该疗法独有特点及疫情严峻形势对临床试验开和及评价带来的问题与挑战,包括临床试验方案设计、干细胞质量管理以及治疗中的伦理考量。只有对其加以重视,才能保证在严峻疫情下安全有效地开展间充质干细胞治疗新型冠状病毒肺炎的临床试验。     

内生细菌对盐胁迫下小麦幼苗脯氨酸和丙二醛的影响

以周麦18为试验材料,以内生菌252和254为供试菌株,试验采用盆栽法设置盐胁迫组、盐胁迫接菌组和对照组,研究不同盐浓度胁迫下接菌处理对小麦幼苗脯氨酸(Pro,proline)和丙二醛(MDA,malondialdehyde)含量的影响。结果表明:小麦幼苗在盐胁迫环境下,随着培养时间和盐浓度增加,盐胁迫组Pro含量先升后降。在前中期,盐胁迫组小麦Pro含量逐渐积累,提高了小麦抗逆性;在后期Pro含量较中期有一定程度下降,小麦逐渐对盐环境产生适应性。随着盐浓度升高,盐胁迫组小麦在不同培养阶段对盐环境的抵抗能力不同,每个时期对盐抵抗能力有一阈值,超过此盐浓度Pro含量下降,抵抗能力减弱。接菌处理后,小麦Pro含量升高,提高了抗盐胁迫能力,第14天时修复效果最明显,接菌252处理组和254处理组分别在盐浓度为200 mmol/L和250 mmol/L时高出盐胁迫组133.48%和91.48%。盐胁迫组MDA含量随时间延长先降后升,与Pro含量变化趋势相反。在前中期,盐胁迫组小麦膜质过氧化程度不高,对小麦正常代谢活动尚未造成严重影响,在后期MDA含量升高,盐胁迫组小麦逐渐枯萎。接菌后,降低了幼苗细胞膜脂化程度,提高了小麦存活率,促进幼苗生长,MDA含量在21 d时均低于盐胁迫组,修复效果显著。     

Association of age with class VI composite restoration

Dental caries is the major oral health problem in most of the countries, affecting 60-90% of school children and a vast majority of adults. Therefore, it is of interest to evaluate the association of age with Class VI defects restored with composite restorations. We used 102 cases with data regarding Class VI composite restorations in a datasheet of 86,000 records at Saveetha Dental College, India for this study. Data shows that Class VI restorations were commonly seen in upper anterior teeth in the age group of 51 and above. The cavities prepared to receive Class VI restoration followed a conservative design of caries removal and used direct restoration techniques for reconstruction of the lost tooth structure.     

普通烟草NtODB基因的电子克隆、表达及生物信息学分析

ODB基因在植物同源重组依赖性的DNA双键断裂修复过程中起重要作用,对植物诱变育种具有潜在的应用价值。克隆烟草NtODB基因并分析其表达特征为丰富ODB基因在同源重组DNA修复过程中的作用提供证据。为得到烟草NtODB基因序列,采用电子克隆技术获得该基因cDNA序列并克隆验证。进一步使用生物信息学方法分析该基因表达特征,对预测蛋白的理化性质、信号肽、高级结构等进行预测。生物信息学分析结果表明,NtODB基因开放阅读框包含579个碱基,蛋白含192个氨基酸残基,NtODB蛋白具有碱性和亲水性,主要定位于细胞质内;实时荧光定量PCR检测结果显示NtODB基因在不同组织中呈现组成型表达特征;亚细胞定位检测提示NtODB主要表达于细胞膜和叶绿体。NtODB基因的克隆与表达分析及其蛋白高级结构和理化性质的预测,可为进一步丰富ODB基因在同源重组依赖的DNA修复系统中的作用机制提供证据。     

超声引导下QLB复合气管插管全麻对于老年患者TEP腹股沟疝无张力修补术影响因素分析

摘要 目的：探讨与分析超声引导下腰方肌阻滞(quadratus lumborum block,QLB)复合气管插管全麻对于老年患者腹腔镜下全腹膜外（totally extraperitoneal prosthetic,TEP）腹股沟疝无张力修补术的影响,以促进该方法的临床使用。方法：2014年9月到2020年6月选择在本院诊治的腹股沟疝老年患者180例,根据随机数字表法分为QLB组与对照组各90例。所有患者都给予腹腔镜下全腹膜外腹股沟疝无张力修补术,对照组给予气管插管全麻,QLB组在对照组麻醉的基础上给予超声引导下QLB,记录两组镇痛与麻醉效果。结果：两组的术中出血量、手术时间等对比差异无统计学意义(P>0.05),QLB组的术后住院时间、术后胃肠功能恢复时间、术后下床活动时间显著短于对照组(P<0.05)。与术后12 h对比,两组术后24 h与36 h的疼痛VAS评分均降低(P<0.05),且QLB组术后12 h、24 h与36 h的疼痛VAS评分都显著低于对照组(P<0.05)。QLB组术后7 d的血肿、呼吸抑制、脏器损伤、腹股沟区包块等并发症发生率为8.9 %,显著低于对照组的21.1 %(P<0.05)。QLB组的瑞芬太尼用量、术后48 h内有效按压自控静脉镇痛泵次数、自控静脉镇痛泵累计用量都显著少于对照组(P<0.05)。结论：超声引导下QLB复合气管插管全麻在老年患者腹腔镜下全腹膜外腹股沟疝无张力修补术中的应用能提高镇痛与麻醉效果,减少术后并发症的发生,有利于促进患者康复。     

双孢蘑菇对高温胁迫的响应及耐热机理

本研究以双孢蘑菇Agaricus bisporus工厂化菌株A15和筛选得到的耐高温菌株A15-TH为研究对象,比较了高温胁迫对两个菌株菌丝生长的影响,并从氧化损伤修复及基础碳代谢-糖酵解途径两个角度探索双孢蘑菇对高温胁迫的响应及耐热机理。高温胁迫下,对照菌株A15的菌丝生长速度降低,菌丝分叉增加;而耐高温菌株A15-TH菌丝生长速度高于A15,菌丝形态优于对照菌株,表现出对高温具有一定的耐受性。对两个菌株高温胁迫下氧化损伤及抗氧化酶系统进行研究发现,高温胁迫30-90min导致对照菌株A15的三磷酸腺苷（ATP）含量下降54.4%-59.6%,线粒体复合物I、II、III活性升高,超氧阴离子（O₂^-）含量增加了34.9%-71.3%;此外高温胁迫降低了超氧化物歧化酶（SOD）的活性,影响了O₂^-的清除效率。耐高温菌株在受到高温胁迫后的氧化损伤及氧化修复效果与对照菌株不同,一方面体现在正常状态下维持较低的细胞能量代谢和较高的ROS合成量;另一方面抗氧化系统中sod1、sod2、cat1与对照菌株相比有不同程度的上调,SOD和过氧化氢酶（CAT）活性增强,可以更有效地清除过量的活性氧,减轻高温对菌丝的氧化损伤。尤其在高温胁迫120min时,A15的线粒体功能及抗氧化系统受到严重损伤,线粒体复合物I、II、III活性和CAT活性大幅度下降,但是A15-TH线粒体复合体I、III活性分别增加至正常状态下的1.4倍和8.9倍,CAT活性比对照菌株高128%,维持了正常的线粒体功能及对活性氧的有效清除。进一步研究发现高温胁迫下,双孢蘑菇菌丝的己糖激酶和丙酮酸激酶活性增加,糖酵解途径加快;耐高温菌株A15-TH在正常状态下和高温胁迫下,己糖激酶和丙酮酸激酶的活性均高于对照菌株A15,具有更活跃的碳代谢。