Antibody dynamics to SARS-CoV-2 in asymptomatic COVID-19 infections

Background

The missing asymptomatic COVID-19 infections have been overlooked because of the imperfect sensitivity of the nucleic acid testing (NAT). Globally understanding the humoral immunity in asymptomatic carriers will provide scientific knowledge for developing serological tests, improving early identification, and implementing more rational control strategies against the pandemic.

Measure

Utilizing both NAT and commercial kits for serum IgM and IgG antibodies, we extensively screened 11 766 epidemiologically suspected individuals on enrollment and 63 asymptomatic individuals were detected and recruited. Sixty-three healthy individuals and 51 mild patients without any preexisting conditions were set as controls. Serum IgM and IgG profiles were further probed using a SARS-CoV-2 proteome microarray, and neutralizing antibody was detected by a pseudotyped virus neutralization assay system. The dynamics of antibodies were analyzed with exposure time or symptoms onset.

Results

A combination test of NAT and serological testing for IgM antibody discovered 55.5% of the total of 63 asymptomatic infections, which significantly raises the detection sensitivity when compared with the NAT alone (19%). Serum proteome microarray analysis demonstrated that asymptomatics mainly produced IgM and IgG antibodies against S1 and N proteins out of 20 proteins of SARS-CoV-2. Different from strong and persistent N-specific antibodies, S1-specific IgM responses, which evolved in asymptomatic individuals as early as the seventh day after exposure, peaked on days from 17 days to 25 days, and then disappeared in two months, might be used as an early diagnostic biomarker. 11.8% (6/51) mild patients and 38.1% (24/63) asymptomatic individuals did not produce neutralizing antibody. In particular, neutralizing antibody in asymptomatics gradually vanished in two months.

Conclusion

Our findings might have important implications for the definition of asymptomatic COVID-19 infections, diagnosis, serological survey, public health, and immunization strategies.

     

脊髓型颈椎病对周围神经传导的影响

目的：探讨颈脊髓损伤对周围神经功能的影响。方法：对３２例脊髓型颈椎病患者分别于术前、术后１～５天及３个月三次检测周围神经传导速度。结果：术前下肢远段感觉神经传导速度和波幅异常者占８１％，于术后３个月内复查发现已明显恢复。结论：颈脊髓损伤对下肢远段感觉神经传导功能有影响     

利用穿梭质粒快速构建含乙型肝炎病毒表面抗原（HBsAg …

目的 应用新型杆状病毒表达系统快速构建含有ＨＢｓＡｇ基因的重组杆状病毒，高效表达ＨＢｓＡｇ，为ＨＢＶ诊断试剂、疫苗及治疗研究提供依据。方法 构建含有ＨＢｓＡｇ基因的供体质粒ｐＦＢ－ＢＳ，转化Ｂａｃ－ｔｏ－Ｂａｃ杆状病毒表达试剂盒中的ＤＨ１０Ｂａｃ致敏菌，利用其含有的细菌Ｔｎ７转座繁忙将ＨＢｓＡｇ基因重组至穿梭质粒Ｂａｃｍｉｄ上，快速筛选出含有ＨＢｓＡｇ基因的重组杆状病毒。结果 此重组病毒能在昆虫细     

静息时或运动后Q—Tc延长诊断冠心病价值的探讨

用自行设计的踏车多指标心血管功能评价系统(E系统),对正常人,冠心病患者、心肌梗塞患者三组进行踏车运动前后Q—Tc变化及运动前后心血管功能评定。对静息时或运动后Q—Tc延长诊断冠心病价值及运动前后心血管功能变化规律的敏感性、特殊性分别进行对照和探讨。     

Role for recombinant gamma-glutamyltransferase from Treponema denticola in glutathione metabolism

Volatile sulfur compounds, including hydrogen sulfide (H(2)S), have been implicated in the development of periodontal disease. Glutathione is an important thiol source for H(2)S production in periodontal pockets. Our recent studies have delineated a pathway of glutathione metabolism in Treponema denticola that releases H(2)S. In this pathway, gamma-glutamyltransferase (GGT) has been proposed to catalyze the first step of glutathione degradation. We have cloned the gene of GGT from T. denticola, which contains an open reading frame of 726 bp encoding a protein of 241 amino acids. Transformation of this gene into Escherichia coli led to the expression of a recombinant protein. After purification by chromatography, the recombinant protein showed enzymatic activity typical of GGT, catalyzing the degradation of Na-gamma-glutamyl-4-nitroaniline (GNA) and the hydrolysis of glutathione, releasing glutamic acid or glutamine and cysteinylglycine. L-Cysteine is not a substrate of GGT. Importantly, GNA, when added to T. denticola, was able to compete with glutathione and inhibit the production of H(2)S, ammonia, and pyruvate. This was accompanied by the suppression of hemoxidative and hemolytic activities of the bacteria. Purified GGT was inactivated by TLCK (Nalpha-p-tosyl-L-lysine chloromethyl ketone) and proteinase K treatment. However, higher enzymatic activity was demonstrated in the presence of 2-mercaptoethanol and dithiothreitol. Our further experiments showed that the addition of recombinant GGT to Porphyromonas gingivalis, a bacterium without significant glutathione-metabolizing capacity, drastically increased the utilization of glutathione by the bacterium, producing H(2)S, ammonia, and pyruvate. This was again accompanied by enhanced bacterial hemoxidative and hemolytic activities. Together, the results suggest an important role for GGT in glutathione metabolism in oral bacteria.     

病毒载量和T淋巴细胞计数在HIV感染者临床治疗疗效观察中的应用

目的 研究病毒载量检测和CD4^ 计数在评价人类免疫缺陷病毒(HIV)感染者疗效中的应用效果。方法 对HIV感染者临床病例73例进行了实验室和临床观察，其中包括6例鸡尾酒治疗病例、36例中药试验性治疗病例及31例未进行治疗的感染者。主要实验室指标包括血浆病毒载量及T淋巴细胞亚群计数。结果 在进行治疗后3个月时联合治疗组的病毒载量明显低于其他两组，并且在其后保持在很低的水平，CD4^ 计数水平明显高于其他两组并在其后持续升高。在整个观察期间，中药治疗组的病毒载量检测和CD4^ 计数水平与未治疗组差异无显著性，但在临床症状观察中中药治疗组较未治疗组有明显改善。结论 病毒载量检测和CD4^ 计数试验是评价抗HIV治疗疗效的有效方法。     

在戊四氮致痫大鼠早期前脑中OX-42和Fos蛋白的表达变化

研究大鼠在戊四氮导致癫痫发作早期前脑内小胶质细胞的变化及其与神经元的关系,本研究应用免疫组织化学法分别显示前脑内OX-42和Fos蛋白表达的时程变化,并用双重标记显示OX-42和Fos阳性细胞的相互关系。结果发现:在戊四氮导致大鼠癫痫发作早期(从15min到360min),前脑的小胶质细胞OX-42表达阳性,随着存活时间的变化,OX-42的阳性反应经历逐渐升高又降低的过程;Fos蛋白在神经元和小胶质细胞中有表达,也呈现逐渐升高又降低的变化;Fos在小胶质细胞表达高峰的时间早于在神经元的表达;另外OX-42阳性小胶质细胞和Fos阳性神经元在前脑分布基本相同,主要分布在大脑皮层、海马、杏仁核等部位。以上结果表明,前脑的小胶质细胞和神经元一样在戊四氮所致癫痫发作的早期表现明显的反应,但小胶质细胞反应的意义有待进一步研究。     

Reciprocal modification of Fas activation and stress protein response decides apoptosis or resistance development of cells

Activation of heat shock factor (HSF)-1 DNA binding and heat shock protein (hsp)-70 expression enable resistance of cells to various forms of stress and maintain cell survival. Fas, a membrane-bound protein, is a central pro-apoptotic factor. Its activation leads to a cascade of events resulting in programmed cell death. Herein, these two mechanisms with contrary functions, promoting either cell survival or death, were addressed for their potential to inhibit each other's activation. Induction of Fas-mediated signalling was followed by a rapid decrease of HSF1 DNA binding and inducible hsp70 expression. Inhibition of HSF1 DNA binding was demonstrated to be based on absent hyperphosphorylation of HSF1 during FAS-signalling. These effects of Fas-activation on the HSF1/hsp70 stress response were blocked by ICE (caspase 1)-inhibitors, suggesting an ICE-mediated process. Furthermore, inhibition of HSF1/hsp70 was accompanied by an increase of apoptosis rates from 20% to 50% in response to heat stress. When analyzing Fas-mediated apoptosis in the presence of HSF1/hsp70 activation, decreased apoptosis rates were detected with induced expression of hsp70 but not with activation of HSF1-DNA binding alone. Thus, we conclude that inhibition of the HSF1/hsp70 stress response during Fas-mediated apoptosis and vice versa may facilitate a cell to pass a previously chosen pathway, stress resistance or apoptosis.     

胫骨平台骨折的现代治疗探讨

目的总结近年来治疗胫骨平台骨折的经验教训，为临床选择更好的治疗方法、提高胫骨平台骨折手术疗效提供参考。方法回顾分析自2001-2007年收治的胫骨平台骨折89例，其中按照Schatzker分型复杂胫骨平台骨折（Ⅴ型，Ⅵ型）67例，男性75例，女性14例。均行切开复位，严格按照内固定原则分别采用螺丝钉和／或外固定架、钢板、微创内固定系统固定骨折进行治疗，必要时辅以关节镜探查镜下手术。结果75例得到随访，最短6个月，最长6年，平均31个月。骨折均愈合，疗效评定参照Merchant标准，术后6个月优良率为81．6％，术后1年优良率为89．3％。结论胫骨平台骨折应当考虑手术治疗，周密的术前计划、妥善处理软组织损伤、正确选择切口、灵活应用内外固定物及关节镜辅助均是手术成功的重要因素。     

异种神经脱细胞移植物修复周围神经缺损的实验研究

目的 探讨异种神经脱细胞移植物桥接大鼠坐骨神经缺损后的神经再生及其再生过程中免疫排斥反应. 方法用脱细胞兔周围神经作为移植物桥接大鼠坐骨神经1 cm缺损;术后3、5、8、11、15天检测血液中淋巴细胞占白细胞百分比;3个月后取移植物及腓肠肌,用甲苯胺蓝、乙酰胆碱酯酶（AchE）、琥珀酸脱氢酶（SDH）组化染色,光、电镜观察神经再生及腓肠肌运动终板的恢复情况. 结果术后大鼠血液中淋巴细胞占白细胞的百分比与正常大鼠相比较无显著性差异,3个月后大鼠术侧下肢足趾能分开,行走时后蹬动作有力,针刺足底有逃避反应,桥接物内见有大量再生的坐骨神经纤维,腓肠肌肌纤维上见有呈AchE阳性的运动终板和神经纤维.结论 异种神经脱细胞移植物桥接大鼠坐骨神经缺损具有促进其再生的作用.