RRLC-UV法同时测定丹参中酚酸类成分的含量

目的:建立RRLC-UV法同时测定丹参药材中9种酚酸的含量.方法:以3,4-二羟基苯乙酸为内标,采用Agilent Zorbax Eclipse Plus C_(18)(2.1 mm×50 mm,1.8μm)色谱柱,以乙腈-0.1%甲酸溶液为流动相梯度洗脱,流速0.3 mL·min~(-1),检测波长质量286 nm.结果:这9种成分在测定质量浓度范围内与色谱峰面积线性关系良好,相关系数不低于0.999 5.仪器精密度和方法精密度RSD均小于2.4%,9种成分平均回收率在96.7%～102.6%,RSD均小于3.1%(n=3).结论:该方法简便、快速,结果准确,重复性好,适用于丹参药材的质量控制.     

辣椒碱-羟丙基-β-环糊精包合物制备鉴定及 热力学稳定性研究

目的:制备及鉴定辣椒碱-HP-β-CD包合物,并考察辣椒碱和HP-β-CD之间的包合摩尔比及包合过程的热力学常数.方法:采用饱和水溶液法制备辣椒碱-HP-β-CD包合物,以差示扫描量热法(DSC)、X射线衍射法(XRD)和红外光谱法(IR)对包合物进行鉴定,通过表观溶解度法考察包合物中主客分子之间的包合摩尔比及包合过程的热力学常数.结果:25,35,45℃下辣椒碱和HP-β-CD能形成1:1摩尔比包合物,相溶解度图呈A_L型.结论:辣椒碱-羟丙基-β-环糊精包合物能显著增大药物的溶解度.     

长毛香科科化学成分及生物活性研究

目的:研究长毛香科科化学成分及生物活性.方法:采用各种色谱法分离,运用多种波谱技术和X-衍射鉴定结构;利用体外DPPH微量抗氧化模型、α-葡萄糖苷酶抑制模型和纸片扩散法进行抑菌活性筛选.结果:从长毛香科科醋酸乙酯部位分离鉴定了8个化合物:三(十八酸)甘油酯(1),2,5-二氧环戊酮(2),羊齿烯醇(3),△~(5,22)-豆甾烯醇(4),24-去亚甲胆甾-5,22(E)-二烯-3β-醇(5),α-菠菜甾醇(6),3,4-二羟基苯丙烯酸乙二醇单酯(7),3,4-二羟基苯丙烯酸(8).结论:化合物1～8为首次从该属中分离得到.生物活性测试结果表明化合物3[IC_(50)=(37.63±3.45)mg·L~(-1)],6[IC_(50)=(178.92±4.99)mg·L~(-1)]和8[IC_(50)=(44.32±7.02)mg·L~(-1)]体外抑制α-糖苷酶抑制活性远高于对照acarbose[IC_(50)=(1 081.27±12.3)mg·L~(-1)];化合物7[IC_(50)=(4.81±0.96)mg·L~(-1)]和8[IC_(50)=(4.16±0.11)mg·L~(-1)]抗氧化活性高于对照BHT[IC_(50)=(35.64±0.36)mg·L~(-1)]和BHA[IC_(50)=(8.74±0.39)mg·L~(-1)];化合物5～8均对小麦赤霉病有明显的抑制活性;化合物5和8对番茄灰霉病菌有明显抑制效果.     

Structure and dynamics of SARS-CoV-2 proofreading exoribonuclease ExoN

High-fidelity replication of the large RNA genome of coronaviruses (CoVs) is mediated by a 3′-to-5′ exoribonuclease (ExoN) in nonstructural protein 14 (nsp14), which excises nucleotides including antiviral drugs misincorporated by the low-fidelity viral RNA-dependent RNA polymerase (RdRp) and has also been implicated in viral RNA recombination and resistance to innate immunity. Here, we determined a 1.6-Å resolution crystal structure of severe acute respiratory syndrome CoV 2 (SARS-CoV-2) ExoN in complex with its essential cofactor, nsp10. The structure shows a highly basic and concave surface flanking the active site, comprising several Lys residues of nsp14 and the N-terminal amino group of nsp10. Modeling suggests that this basic patch binds to the template strand of double-stranded RNA substrates to position the 3′ end of the nascent strand in the ExoN active site, which is corroborated by mutational and computational analyses. We also show that the ExoN activity can rescue a stalled RNA primer poisoned with sofosbuvir and allow RdRp to continue its extension in the presence of the chain-terminating drug, biochemically recapitulating proofreading in SARS-CoV-2 replication. Molecular dynamics simulations further show remarkable flexibility of multidomain nsp14 and suggest that nsp10 stabilizes ExoN for substrate RNA binding to support its exonuclease activity. Our high-resolution structure of the SARS-CoV-2 ExoN–nsp10 complex serves as a platform for future development of anticoronaviral drugs or strategies to attenuate the viral virulence.

The 29.9-kb single-stranded RNA genome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the global COVID-19 pandemic, is replicated and transcribed by the viral RNA-dependent RNA polymerase (RdRp, nsp12) (1–3). Unlike the high-fidelity cellular replicative DNA polymerases, viral RdRp enzymes, including the CoV RdRp, do not contain a proofreading exonuclease domain to ensure high fidelity. The resulting higher mutation rate (10⁻⁴ to 10⁻⁶ substitutions per nucleotide per round of replication) is generally thought to promote rapid viral adaptation in response to selective pressure (4–6). However, the lack of proofreading activity in RdRp poses a particular challenge for the replication of CoVs, which feature the largest known RNA virus genomes (27 to 32 kb, up to twice the length as the next-largest nonsegmented RNA viral genomes) (7, 8). It has been reported that SARS-CoV nsp12 is the fastest viral RdRp known but with an error rate more than one order of magnitude higher than the generally admitted error rate of viral RdRps (9), clearly necessitating a unique proofreading mechanism.To mitigate the low fidelity of RdRp, all coronaviruses encode a 3′-to-5′ exoribonuclease (ExoN) in multifunctional nsp14 (10–12), which forms a complex with nsp10 critical for the ExoN activity, and additionally contains a C-terminal guanine N7 methyl transferase (N7-MTase) domain. Mutations of SARS-CoV-2 nsp14 exhibit strong association with increased genome-wide mutation load (13, 14), and genetic inactivation of ExoN in engineered SARS-CoV and murine hepatitis virus (MHV) leads to 15- to 20-fold increases in mutation rates (7, 15, 16). Furthermore, in a mouse model, SARS-CoV with inactivated ExoN shows a mutator phenotype with decreased fitness and lower virulence over serial passage, suggesting a potential strategy for generating a live, impaired-fidelity coronavirus vaccine (17). Alternatively, recent studies show that ExoN inactivation abrogates replication of SARS-CoV-2 and Middle East Respiratory Syndrome CoV (18), hinting at additional functions for ExoN in viral replication. Indeed, ExoN activity has been reported to mediate the extensive viral RNA recombination required for subgenomic messenger RNA (mRNA) synthesis during normal replication of CoVs, including SARS-CoV-2 (19), and it was shown to be required for resistance to the antiviral innate immune response for MHV (20). ExoN inactivation also significantly increases the sensitivity of CoVs to nucleoside analogs that target RdRp, which is consistent with the biochemical activity of ExoN to excise mutagenic or chain-terminating nucleotides misincorporated by RdRp (21–23). These observations combine to suggest that chemical inhibition of ExoN could be an effective antiviral strategy against CoVs. In this study, we determined high-resolution crystal structures of the SARS-CoV-2 ExoN–nsp10 complex and studied its biochemical activities. Furthermore, we used molecular dynamics (MD) simulations to better understand the dynamics of nsp14, nsp10, and their interaction with RNA.     

Identification of Fenton-like active Cu sites by heteroatom modulation of electronic density

Developing heterogeneous catalysts with atomically dispersed active sites is vital to boost peroxymonosulfate (PMS) activation for Fenton-like activity, but how to controllably adjust the electronic configuration of metal centers to further improve the activation kinetics still remains a great challenge. Herein, we report a systematic investigation into heteroatom-doped engineering for tuning the electronic structure of Cu-N₄ sites by integrating electron-deficient boron (B) or electron-rich phosphorus (P) heteroatoms into carbon substrate for PMS activation. The electron-depleted Cu-N₄/C-B is found to exhibit the most active oxidation capacity among the prepared Cu-N₄ single-atom catalysts, which is at the top rankings of the Cu-based catalysts and is superior to most of the state-of-the-art heterogeneous Fenton-like catalysts. Conversely, the electron-enriched Cu-N₄/C-P induces a decrease in PMS activation. Both experimental results and theoretical simulations unravel that the long-range interaction with B atoms decreases the electronic density of Cu active sites and down-shifts the d-band center, and thereby optimizes the adsorption energy for PMS activation. This study provides an approach to finely control the electronic structure of Cu-N₄ sites at the atomic level and is expected to guide the design of smart Fenton-like catalysts.

The Fenton-like process presents one of the most powerful water treatment technologies to tackle persistent organic pollutants resulting from rapid economic development and unsustainable industrial and agricultural expansion (1 –4). The peroxymonosulfate (PMS)-based advanced oxidation process has attracted extensive attention due to its high efficiency at a wide pH range and ease of transport and storage (5 –7). However, the sluggish kinetics of PMS activation during oxidation processes results in prohibitive costs and substantial chemical inputs (8, 9). Therefore, developing efficient catalysts to accelerate the reaction kinetics of PMS is crucial toward efficient catalytic oxidation of recalcitrant organics. Although homogeneous first-row transition metals (Co²⁺, Fe²⁺, Cu²⁺, and Mn²⁺) generally exhibit remarkable capabilities for PMS activation, they also suffer problems such as poor recyclability and accumulation of sludge (10 –12). Comparatively, heterogeneous catalysts [e.g., transition metal oxides (13, 14), supported nanoparticles (NPs) (15, 16), and carbon-based materials (17, 18)] can be readily recovered and regenerated and are recognized as promising candidates for PMS activation. Nevertheless, the heterogeneity of NPs results in lower utilization efficiency of surface atoms (with 81.6% atoms buried and unavailable for 6-nm nickel NPs) and generally slower reaction kinetics than their homogeneous counterparts (19).Single-atom catalysts (SACs) featuring utmost atom-utilization efficiency and tunable electronic structure can break the limitations of heterogeneous catalysts in terms of the kinetics and catalytic activity (20, 21). Thus, SACs show a great potential to address the slow reaction kinetics of PMS for the Fenton-like process via maximizing the number of catalytic sites (22). For instance, a single-site Fe catalyst exhibited much faster reaction kinetics toward the degradation of phenol than the Fe NP catalyst, owing to the maximized atomic utilization (23). In addition, the synergetic effect between the atomic center and pyrrolic N site of supports endowed Co SACs with dual reaction sites and high activity for PMS-based oxidation (24). To further accelerate the reaction kinetics of PMS, various strategies have been developed to improve the intrinsic activity of single atomic sites. By controlling the configurations of single atomic sites, PMS was more favorable for adsorption and activation on the CoN_2 + 2 site than the CoN₄ site (25). Previous work shows that manipulating the electronic structure of single sites plays an essential role in mediating the intrinsic activity (26, 27). It is highly desirable to gain insights into tuning the electronic structure of single-atom sites to achieve superior PMS activation kinetics.Recent studies demonstrate that the electronic structure of isolated metal sites can be directly modulated by altering the coordinated atom species of the metal centers, favorable for expediting catalytic activity (28, 29). Notably, controlling the long-range interactions with suitable functionalities on the substrate of SACs can be a promising approach for tuning the electronic structure of metal centers (30). Indeed, the kinetic activity of single atomic sites was successfully tuned by the introduction of electron-withdrawing oxidized S groups or electron-donating thiophene-like S species into carbon supports of SACs (31). To this end, nonmetallic heteroatoms offer a substantial potential to serve as electron-withdrawing/donating functionalities on the carbon plane by chemical substitution (32, 33). Specifically, boron (B) with a vacant 2p_z orbital conjugating with the carbon π system extracts the electrons, while phosphorus (P) with a readily available lone electron pair and low electronegativity is expected to donate electron in graphene (34, 35). With this strategy, incorporating particular heteroatoms (B/P) into the substrate is a possible route to deplete/enrich the electronic density of metal centers, tuning the electronic structure of single sites to promote PMS activation kinetics.In this work, we designed a versatile strategy to systematically tune the electronic structure of Cu-N₄ sites by integrating specific heteroatoms (B/P) into N-doped carbon substrates of Cu SACs. Subsequently, the effect of the controlled electronic features of Cu centers on facilitating PMS reaction kinetics was explored. Here, the heteroatom modified Cu-N₄ catalysts were first prepared by using a hydrogen-bonding-assisted pyrolysis approach. Synchrotron X-ray adsorption spectroscopy and the projected density of states (PDOS) analysis verified the successful regulation of the electronic configuration of the Cu-N₄ SACs by different heteroatom functionalities. Furthermore, electron paramagnetic resonance and Raman spectra were employed to elucidate the PMS activation mechanism in the Cu-N₄/C-B/PMS system. This study opens an avenue to regulating the electronic structures of single active site of SACs to accelerate PMS activation kinetics for pollutant degradation.     

电子束CT和超声心动图在诊断先天性心脏病中的对照研究

目的 探讨电子束CT(electron beam computed tomography,EBCT)和超声心动图在先天性心脏病(简称先心病)诊断中的价值.方法 32例经临床及经胸超声心动图(transthoracic echocardiography,TTE)诊断为先心病的患者进行EBCT心血管造影检查,与导管法心血管造影检查和手术结果进行对照.结果 32例患者中,EBCT总体诊断符合率87.5%(28/32),TTE诊断符合率78.1%(25/32).EBCT对心外及大血管与房室连接诊断准确率为96.6%(57/59),明显优于TTE的66.1%(39/59).而TTE对心内畸形的诊断准确率为97.7%(43/44),高于EBCT的81.8%(36/44).EBCT与TTE两者结合,可将诊断准确率提高为96.9%(31/32).结论 EBCT对先天性心脏病有重要的诊断价值,尤其对心外及大血管与房室连接关系诊断准确率较高.将EBCT与TTE检查相结合,可大大提高对各种先心病的诊断准确率.     

中、小面积深度烧伤符合功能与美学要求的皮肤移植术

目的:探讨非面颈部中、小面积深度烧伤更加符合人体皮肤功能与美学要求的皮肤移植技术.方法:受皮区创面采用浅切痂、削痂法,尽可能多保留创面正常皮下组织,严密止血.以低浓度肾上腺素生理盐水皮下注射肿胀供皮区,鼓式取皮机、电动切皮机或滚轴取皮刀切取厚0.2～0.6 mm大张中厚断层皮;游离皮片长轴垂直于受区纵轴不开洞移植.皮片与创缘、皮片与皮片3-0丝线严密缝合,妥善包扎、制动.结果:接受改进的皮肤移植术的患者共592例,受区面积为1%～30%[平均(11.2±2.7)%]TBSA.全部病例移植皮片成活率＞95%,移植皮片100%成活者91.9%(544/592),随访1 a以上评价,受区皮肤组织丰满,质地柔软、光滑,无明显增生性瘢痕,肢体关节活动自如,轻度色素沉着,供皮区表面较正常皮肤略粗糙,色素沉着不明显.结论:加强创面处理,改进和熟练掌握取皮技术,选择合适供区,中、小面积深度烧伤采用大张中厚和薄中厚断层皮不开洞移植,供皮区和修复部位均获得较理想的功能与美容效果.     

心得力对心肌病大鼠心功能及衰竭心肌线粒体的作用

目的:研究心得力(Xindly)对阿霉素(ADR)心肌病大鼠心功能及衰竭心肌线粒体的影响,部分探讨其治疗心肌病的分子机制.方法:SD大鼠50只随机分为正常组,ADR心肌病心衰模型组(含安慰剂组,达爽组和心得力 达爽组).药物干预4 wk后用Hp Sonos 2500型多功能超声检查仪无创检测各组大鼠心脏射血分数(EF),左心室舒张末内径(LVDD),左心室收缩末内径(LVDS);用透射电镜(H-600)及医学图像分析软件计量心肌线粒体面积(Area),线粒体积分光密度(IOD),线粒体周长(Margination),线粒体直径(Diameter),线粒体平均面积(Per Area).结果:①心得力 达爽组心功能较安慰剂组改善,左室收缩末内径较达爽组改善(P＜0.05).②心得力 达爽组心肌细胞线粒体Per Area,Margination,IOD均好于安慰剂组与达爽组(P＜0.05).结论:心得力 达爽治疗心肌病有疗效.     

炎症在衰老与衰老相关疾病中的作用及机制研究进展

中国人口老龄化问题日趋严峻。延缓组织器官衰老,预防和治疗衰老相关的疾病,制定干预和延缓衰老的安全有效策略已成为亟待解决的重要科学问题。慢性炎症累积促进细胞及机体衰老,是多组织器官衰老的共性特征之一。本文综述了炎症在衰老及衰老相关疾病中的作用及调控机制,以及靶向干预炎症信号延缓衰老的最新研究进展。     

原发性高血压患者发生心房颤动的危险因素及其预测价值

目的探讨原发性高血压患者发生心房颤动的危险因素及其预测价值。方法选取2018年1月至2019年10月在安徽省第二人民医院心内科住院的原发性高血压患者共104例,根据患者有无心房颤动分为观察组(高血压合并房颤,38例)和对照组(高血压未合并房颤,66例),分别对两组一般资料(性别、年龄、高血压病程、吸烟饮酒史、家族史、糖尿病史)、血液生化指标[三酰甘油、总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇(LDL-C)、尿酸、肌酐、尿素氮、血浆D二聚体、空腹血糖、纤维蛋白原、血红蛋白、同型半胱氨酸(HCY)]及心脏超声参数[左心房内径(LAD)、室间隔厚度(IVST)、左心室后壁厚度(LVPWT)、右心室内径(RVD)、左心室射血分数(LVEF)]进行单因素、多因素分析,同时通过受试者工作特征(ROC)曲线分析相关指标对此类患者并发心房颤动的预测价值。结果多因素logistic回归分析结果显示,LAD及LVPWT大、HCY高、LDL-C低是原发性高血压患者发生心房颤动的危险因素(P<0.05)。ROC曲线结果显示,LAD、LVPWT、HCY、LDL-C对原发性高血压患者发生心房颤动均具...