Max试验验证症状限制心肺运动试验为最大极限运动进一步临床研究*

目的: 验证临床受试者所完成的心肺运动试验（CPET）为最大极限运动,进一步设计完善Max试验验证CPET结果客观定量功能评估的准确性及以某特定指标的特定数值作为停止运动的标准是否可行。方法: 选择2017年9月至2019年1月在阜外医院签署知情同意书后进行CPET和Max试验受试者216例。其中正常受试者41例,因CPET峰值呼吸交换率（RER）≤1.10,或运动中心率和血压不上升,对CPET极限运动结果存在质疑的临床患者175例进行研究。其中60例已初步报告,本研究进一步扩大研究。Max试验方法：完成CPET测试后,先蹬车≥60 r/min,再施加130%峰值功率的恒定功率,鼓励受试者运动至不能坚持的极限状态。计算分析Max试验30 s的最大心率和最大摄氧量、及其与峰值心率和峰值摄氧量之间的差值和百分差值。百分差值=（Max值-峰值值）/Max值× 100%。评测标准：①若心率和摄氧量任一指标的差值百分比≤-10%（Max测试的数值低于CPET峰值数据）则定义Max试验操作失败,否则为成功;2若心率和摄氧量的差值百分比均在-10%~10%,则Max试验操作成功,证明CPET数据为极限运动,CPET 峰值相关数据较为准确;③若心率和摄氧量差值任一指标差值百分比≥10%时,则Max试验操作成功,证明CPET结果为非极限运动。结果: 病例组峰值摄氧量（L/min、ml/（min·kg）、%pred）、无氧阈（L/min、ml/（min·kg）、%pred）、峰值氧脉搏（ml/beat、%pred）、峰值RER、峰值收缩压（mmHg）、峰值运动负荷（W/min）、峰值心率（bpm）、摄氧有效性峰值平台（OUEP）（比值、%pred）低于正常组,二氧化碳通气有效性平均90 s最低值（Lowest Ve/VCO₂）（比值、%pred）、二氧化碳通气效率斜率（Ve/VCO₂ Slope）（比值、%pred）高于正常组（P<0.05）。所有正常组与病例组均安全无任何事件完成CPET和Max试验。216例受试者中,Max试验成功198例（91.7%）,其中证明CPET为极限运动182例,为非极限运动16例;失败18例（8.3%）。结论: 在临床检查中,若对CPET结果是否为最大极限存在质疑,利用Max试验可验证CPET是否为极限运动。Max试验方法安全可行,值得进一步深入研究和临床推广应用。     

新生儿首次呼吸前后脐带动静脉血液氧和二氧化碳变化探索呼吸调控机制的初步报告II—同一个新生儿同一时间的脐带动静脉血液氧和二氧化碳分压差值个体化分析*

目的: 为探讨新生儿自主呼吸产生机制,前文已对新生儿出生后自主呼吸开始前脐带动静脉氧气和二氧化碳差值进行了人群组间分析;而本部分则对相关信息进行个体化分析。方法: 在产前经所有胎儿父母签署知情同意书,新生儿出生后还没有呼吸之前在脐带动脉和脐带静脉分别连续逐搏取血,仅有3例同时采集到Pua和Puv血液样本进行血气分析测定,计算分析脐带静脉和脐带动脉的异同和动态变化。结果: 虽然准备了数十产妇,但仅有3例同时采集到Pua和Puv血液样本,同一时间的PuvO₂显著高于PuaO₂（P均<0.01）,平均相差（24.17±7.09） mmHg;而PuvCO₂显著低于PuaCO₂（P均<0.01）,平均相差（-7.67±3.70） mmHg。在同一时间的Puv-uaO₂显著高于Puv-uaCO₂（P<0.05）。结论: 新生儿出生后自主呼吸前,全部氧气供应由脐带静脉运输,只要胎盘开始剥离则新生儿的PuaO₂随时间（心跳次数）逐渐降低,当PuaO₂达到触发呼吸阈值（最低值）诱发第一次吸气开始其自主呼吸。     

存在睡眠呼吸异常的慢病患者呼吸影响心率变异性的初步分析*

目的: 基于整体整合生理学医学理论提出的呼吸引起循环指标变异的假说,分析研究存在睡眠呼吸异常的慢病患者睡眠期间呼吸和心率变异之间的相关关系。方法: 纳入存在睡眠呼吸异常且呼吸暂停低通气指数（AHI）≥15次/小时的慢病患者11例,签署知情同意书后完成标准化症状限制性极限运动的心肺运动试验（CPET）和睡眠呼吸监测,计算分析病人睡眠期间波浪式呼吸（OB）期与正常平稳呼吸期的呼吸鼻气流、心电图R-R间期心率变异的规律。结果: 存在睡眠呼吸异常的慢病患者CPET峰值摄氧量（Peak VO₂）和无氧阈（AT）为（70.8±13.6）%pred和（71.2±6.1）%pred;CPET有5例存在运动诱发的波浪式呼吸（EIOB）,6例为呼吸不稳定,提示整体功能状态低于正常人。本组慢病患者AHI为每小时（28.8±10.0）次,睡眠呼吸异常总时间占睡眠总时间的比值为（0.38±0.25）;OB周期的平均时间长度为（51.1±14.4）s。本组慢病患者正常平稳呼吸期的呼吸周期数与心率变异周期数的比值（B-n/HRV-B-n）为1.00±0.04,每个呼吸周期节律的心率变异平均幅度（HRV-B-M）为（2.64±1.59） bpm,虽然低于正常人（P<0.05）,但却与无睡眠呼吸异常的慢病患者相似（P>0.05）;HRV-B-M的变异度CV（HRV-B-M的SD/x）为( 0.33±0.11）,期间血氧饱和度（SpO₂）虽略低,但并无明显规律性下降与上升。本组慢病患者的OB期间呼吸周期数与心率变异周期数（OB-B-n/OB-HRV-B-n）比值为（1.22±0.18）,OB期每个呼吸周期节律的心率变异平均幅度（OB-HRV-B-M）为（3.56±1.57）bpm及其变异度（OB-CV =OB-HRV-B-M的SD/x）为（0.59±0.28）,每个OB周期节律的心率变异平均幅度（OB-HRV-OB-M）为（13.75±4.25）bpm,OB期间低通气时SpO₂出现明显的下降,OB期间SpO₂平均变异幅度（OB-SpO₂-OB-M）为（4.79±1.39）%,OB期的OB-B-n/OB-HRV-B-n比值、OB-HRV-OB-M比其正常平稳呼吸期对应指标显著增大（P<0.01）。OB-HRV-B-M虽然与正常平稳呼吸期HRV-B-M相比差异无统计学意义（P>0.05）,但其变异度OB-CV却显著增大（P<0.01）。结论: 睡眠呼吸异常的慢病患者OB期的心率变异幅度大于其正常平稳呼吸期,当呼吸模式发生改变时心率变异也发生明显改变,其平稳呼吸期的呼吸周期数与心率变异周期数的比值与正常人以及无睡眠呼吸异常的慢病患者相同,证实心率变异为呼吸源性;而其OB期间心率变异周期数相对于呼吸周期减少直接源于此时的低通气或者呼吸暂停,心率变异也是呼吸源性。     

不同水位时期东洞庭湖湿地土壤微生物生物量碳氮和酶活性变化

为从土壤微生物的角度分析东洞庭湖不同植被类型湿地土壤质量状况,本研究选取了苔草、芦苇和柳树3种典型植被类型为对象,在平水期、丰水期和枯水期对其土壤微生物生物量碳(MBC)、氮(MBN)和酶活性进行监测,并分析其主要影响因子。结果表明: 1)3个水位时期,各植被类型湿地土壤MBC、MBN、蔗糖酶和纤维素酶活性(枯水期纤维素酶除外)均表现为0～10 cm高于10～20 cm,而土壤过氧化氢酶活性则相反。2)各植被类型湿地0～20 cm土层土壤MBC、MBN和MBC/TOC(总有机碳)、MBN/TN(总氮)皆以丰水期最低。3)各植被类型湿地0～20 cm土层土壤蔗糖酶活性峰值均出现在枯水期,而纤维素酶活性峰值出现在平水期,过氧化氢酶活性季节性波动较小,以丰水期稍高。4)不同植被类型间比较:平水期和丰水期,芦苇湿地土壤蔗糖酶活性显著高于其他植被类型,而其土壤纤维素酶活性最低,枯水期不同湿地间两种酶活性差异不显著。土壤过氧化氢酶活性在平水期以苔草湿地最高,枯水期以柳树湿地最高,丰水期以芦苇湿地最低。5)相关性分析表明,土壤MBC、MBN和蔗糖酶与TOC、TN、总磷(TP)呈显著正相关,而与pH值呈显著负相关。土壤纤维素酶和过氧化氢酶与TOC、TN、TP呈显著负相关,与pH值呈显著正相关。表明季节性水位波动影响土壤C、N、P和pH值,并对土壤微生物生物量碳、氮和酶活性产生显著影响,使其呈现明显的季节性变化特征。     

Identification and Characterization of a Novel Single Domain Antibody Against Ebola Virus

Virologica Sinica - Ebola virus (EBOV) belongs to the Filoviridae family and causes severe illnesses such as hemorrhagic fever with a high mortality rate up to 90%. Now two antibody drugs termed...     

Sustainability of SARS-CoV-2 Induced Humoral Immune Responses in COVID-19 Patients from Hospitalization to Convalescence Over Six Months

Virologica Sinica - Understanding the persistence of antibody in convalescent COVID-19 patients may help to answer the current major concerns such as the risk of reinfection, the protection period...     

A Multicenter Study of Viral Aetiology of Community-Acquired Pneumonia in Hospitalized Children in Chinese Mainland

Virologica Sinica - Community-acquired pneumonia (CAP) is one of the leading causes of morbidity and mortality in children worldwide. In this study, we aimed to describe the aetiology of viral...     

4种河鲀全基因组微卫星分布特征分析

本研究利用MISA软件对四种河鲀全基因组中的微卫星进行筛选并分析.结果如下:在红鳍东方鲀(Takifugu rubripes)(391.49 Mb)、菊黄东方鲀(T.flavidus)(366.29 Mb)、双斑东方鲀(T.bimaculatus)(371.68 Mb)及黑青斑河鲀(Tetraodon nigroviridis)(342.40 Mb)全基因组中,分别筛选出142 885个、135 009个、147 549个和179 703个完整型微卫星.相对丰度分别为365个/Mb,369个/Mb,397个/Mb和525个/Mb.微卫星总长度分别为2 876 322 bp,2 689 710 bp,3 140 445 bp 和3 615 069 bp,分别占基因组序列总长度的0.73％,0.73％,0.84％和1.06％.在1～6个不同碱基重复类型完整型微卫星中,四种河鲀的6种碱基类型数目排序是一致的.均是单碱基重复数目最多,然后依次是二碱基、三碱基、四碱基、五碱基和六碱基.其中AC,A,C,AG,AGG,AT,AAT和AAC是四种河鲀共有的常见核心重复类别.东方鲀属(Takifugu)三种河鲀基因组微卫星分布特征极为相似,分析红鳍东方鲀和双斑东方鲀的遗传距离可能更为接近.鲀属(Tetraodon)黑青斑河鲀与其他三种东方鲀属河鲀除部分微卫星特征相似外,在微卫星总数、微卫星相对丰度和密度、部分碱基类型数目及类别方面和东方鲀属差距较大.这可能与两属鱼类地理分布及进行滑动复制的碱基组成有关,推测东方鲀属和鲀属基因组可能具有独特的进化机制.本研究为多种河鲀基因组特征分析、多种河鲀微卫星引物设计、不同属种河鲀遗传距离及亲缘关系的探究等奠定了基础.     

Evolution and diversity of axon guidance Robo receptor family genes

The diversity of axon guidance (AG) receptors reflects gains in complexity of the animal nervous system during evolution. Members of the Roundabout (Robo) family of receptors interact with Slit proteins and play important roles in many developmental processes, including AG and neural crest cell migration. There are four members of the Robo gene family. However, the evolutionary history of Robo family genes remain obscure. We analyzed the distribution of Robo family members in metazoan species ranging in complexity from hydras to humans. We undertook a phylogenetic analysis in metazoans, synteny analysis, and ancestral chromosome mapping in vertebrates, and detected selection pressure and functional divergence among four mammalian Robo paralogs. Based on our analysis, we proposed that the ancestral Robo gene could have undergone a tandem duplication in the vertebrate ancestor; then one round of whole genome duplication events occurred before the divergence of ancestral lamprey and gnathostome, generating four paralogs in early vertebrates. Robo4 paralog underwent segmental loss in the following evolutionary process. Our results showed that Robo3 paralog is under more powerful purifying selection pressure compared with other three paralogs, which could correlate with its unique expression pattern and function. Furthermore, we found four sites under positive selection pressure on the Ig1‐2 domains of Robo4 that might interfere with its binding to Slits ligand. Diverge analysis at the amino acid level showed that Robo4 paralog have relatively greater functional diversifications than other Robo paralogs. This coincides with the fact that Robo4 predominantly functions in vascular endothelial cells but not the nervous system.     

Drought stress and plant ecotype drive microbiome recruitment in switchgrass rhizosheath

The rhizosheath, a layer of soil grains that adheres firmly to roots, is beneficial for plant growth and adaptation to drought environments. Switchgrass is a perennial C4 grass which can form contact rhizosheath under drought conditions. In this study, we characterized the microbiomes of four different rhizocompartments of two switchgrass ecotypes (Alamo and Kanlow) grown under drought or well-watered conditions via 16S ribosomal RNA amplicon sequencing. These four rhizocompartments, the bulk soil, rhizosheath soil, rhizoplane, and root endosphere, harbored both distinct and overlapping microbial communities. The root compartments (rhizoplane and root endosphere) displayed low-complexity communities dominated by Proteobacteria and Firmicutes. Compared to bulk soil, Cyanobacteria and Bacteroidetes were selectively enriched, while Proteobacteria and Firmicutes were selectively depleted, in rhizosheath soil. Taxa from Proteobacteria or Firmicutes were specifically selected in Alamo or Kanlow rhizosheath soil. Following drought stress, Citrobacter and Acinetobacter were further enriched in rhizosheath soil, suggesting that rhizosheath microbiome assembly is driven by drought stress. Additionally, the ecotype-specific recruitment of rhizosheath microbiome reveals their differences in drought stress responses. Collectively, these results shed light on rhizosheath microbiome recruitment in switchgrass and lay the foundation for the improvement of drought tolerance in switchgrass by regulating the rhizosheath microbiome.