Antibody responses to SARS-CoV-2 in COVID-19 patients: the perspective application of serological tests in clinical practice

BackgroundWe aim to investigate the profile of acute antibody response in COVID-19 patients, and provide proposals for the usage of antibody test in clinical practice. MethodsA multi-center cross-section study (285 patients) and a single-center follow-up study (63 patients) were performed to investigate the feature of acute antibody response to SARS-CoV-2. A cohort of 52 COVID-19 suspects and 64 close contacts were enrolled to evaluate the potentiality of the antibody test. ResultsThe positive rate for IgG reached 100% around 20 days after symptoms onset. The median day of seroconversion for both lgG and IgM was 13 days after symptoms onset. Seroconversion of IgM occurred at the same time, or earlier, or later than that of IgG. IgG levels in 100% patients (19/19) entered a platform within 6 days after seroconversion. The criteria of IgG seroconversion and > 4-fold increase in the IgG titers in sequential samples together diagnosed 82.9% (34/41) of the patients. Antibody test aided to confirm 4 patients with COVID-19 from 52 suspects who failed to be confirmed by RT-PCR and 7 patients from 148 close contacts with negative RT-PCR. ConclusionIgM and IgG should be detected simultaneously at the early phase of infection. The serological diagnosis criterion of seroconversion or the >; 4-fold increase in the IgG titer is suitable for a majority of COVID-19 patients. Serologic test is helpful for the diagnosis of SARS-CoV-2 infection in suspects and close contacts.

A Peptide-based Magnetic Chemiluminescence Enzyme Immunoassay for Serological Diagnosis of Corona Virus Disease 2019 (COVID-19)

A respiratory illness has been spreading rapidly in China, since its outbreak in Wuhan city, Hubei province in December 2019. The illness was caused by a novel coronavirus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Clinical manifestations related to SARS-CoV-2 infection ranged from no symptom to fatal pneumonia. World Health Organization (WHO) named the diseases associated with SARS-CoV-2 infection as COVID-19. Real time RT-PCR is the only laboratory test available till now to confirm the infection. However, the accuracy of real time RT-PCR depends on many factors, including sampling location and of methods, quality of RNA extraction and training of operators etc.. Variations in these factors might significantly lower the sensitivity of the detection. We developed a peptide-based luminescent immunoassay to detect IgG and IgM. Cut-off value of this assay was determined by the detection of 200 healthy sera and 167 sera from patients infected with other pathogens than SARS-CoV-2. To evaluate the performance of this assay, we detected IgG and IgM in the 276 sera from confirmed patients. The positive rate of IgG and IgM were 71.4% (197/276) and 57.2% (158/276) respectively. By combining with real time RT-PCR detection, this assay might help to enhance the accuracy of diagnosis of SARS-CoV-2 infection.

Predictive Value of Tumor Mutation Burden in Immunotherapy for Lung Cancer / 中国肺癌杂志

The morbidity and mortality of lung cancer is the first in the world, immunotherapy has become a important treatment strategy in addition to chemotherapy, radiotherapy and targeted therapy. In recent years, the US Food and Drug Administration (FDA) has successively approved immunological checkpoint inhibitors as standard programs for non-small cell lung cancer (NSCLC) in second-line or first-line treatment. The National Comprehensive Cancer Network (NCCN) also recommends immunological checkpoint inhibitors as the standard treatment for small cell lung cancer (SCLC). Now, the treatment for lung cancer has entered the era of precision treatment, it is very important to select effective and reliable biomarker for the dominant populations of lung cancer to receive immunotherapy. A large number of researchs indicated that tumor mutation burden (TMB) may be an independent predicted biomarker for immunotherapy, but with limitations. This article reviewed the predictive value of TMB and its limitations in the field of immunotherapy for lung cancer.

Effects of propofol and midazolam on the prognosis of patients treated with noninvasive positive pressure ventilation / 中国基层医药

Objective To compare the effects of propofol and midazolam on the prognosis of patients treated with noninvasive positive pressure ventilation.Methods A prospective,single-blind,randomized controlled trial (RCT) was conducted in 90 patients who were treated with noninvasive ventilation for acute dyspnea in the ICU of the Sixth People's Hospital Affiliated to Shanghai Jiaotong University from October 2014 to December 2016.They were randomly divided into three groups according to the digital table,with 30 cases in each group.The control group was not given sedation treatment.The propofol group was given propofol 0.5 ～ 1 mg/kg,and then administered by intravenous infusion of 1 mg · kg-1 · h-1 with a micropump.The midazolam group was given midazolam 0.05-O.1 mg/kg,and then with intravenous infusion of 0.05-0.1 mg · kg-1 · h-1 maintaining the patients'sedation goals(Ramsay score of 2).The vital signs and blood gas analysis indicators were recorded.The incidence of tracheal intubation,the incidence of hospital infection,length of ICU and hospital stay,mortality and sedation-related complications were compared.Results The tracheal intubation rate in the propofol group was similar to that in the midazolam group (20.0％ vs.23.3％,x2 =2.65,P ＞ 0.05),while the tracheal intubation rate (46.7％) in the control group was significantly higher (x2 =4.21,4.17,all P ＜ 0.05).The length of ICU and hospital stay in the pmpofol group [(7 ± 3)d and (15 ± 5) d] and midazolam treatment group[(8 ± 4) d and (16 ± 4) d] were significantly shorter than those in the control group[(13 ± 4) d and (20 ± 6) d] (t =2.384,2.371,2.392,2.389,all P ＜ 0.05).The mortality rates of 30d (20.0％,6/30) and 90d (30.0％,9/30) in the control group were higher than those in the propofol group(10.0％,3/30;20.0％,6/30),and the midazolam group (13.3％,4/30;23.3％,7/30),but the differences were not statistically significant(P ＞ 0.05).The incidence rates of hospital infection in the pmpofol group and midazolam group were 6.6％ (2 cases) and 10.0％ (3 cases),which were significantly lower than 33.3％ (10 cases) in the control group (x2 =4.32,4.23,all P ＜ 0.05).Conclusion The use of mild sedation in patients of acute dyspnea treated with noninvasive positive pressure ventilation can improve the patients' tolerance rate,reduce the rate of tracheal intubation and the incidence of hospital infection,and decrease the length of ICU and hospital stay,without significant adverse reactions.There was no significant difference between propofol and midazolam.

Associations between Tensin1 protein and clinicopathological characteristics and prognoses of gastric cancer patients / 中华消化外科杂志

Objective To investigate the associations between expression of Tensin1 protein and clinicpathological characteristics and prognoses of gastric cancer (GC) patients.Methods The retrospective casecontrol study was conducted.The clinicopathological data of 163 GC patients who were admitted to the Affiliated Hospital of Jiangsu University between July 31,2011 and December 31,2013 were collected.The GC tissues and adjacent normal tissues were taken to paraffin imbedding,and then were detected by immunohistochemistry.Observation indicator:(1) expressions of Tensinl protein in GC tissues and adjacent normal tissues;(2) association between expression of Tensinl protein in GC tissues and clinicopathological characteristics;(3) followup and survival situations;(4) prognostic factors analysis.Follow-up using telephone interview was performed to detect survival up to January 1,2017.Measurement data with skewed distribution were described as M (range).Count data were analyzed using the chi-square test or pairing chi-square test.The survival curve and rate were respectively drawn and calculated using the Kaplan-Meier method,and Log-rank test was used for survival analysis.The univariate analysis and multivariate analysis were done using the COX roportional hazard model.Results (1) Expressions of Tensinl protein in GC tissues and adjacent normal tissues:immunohistochemistry showed that Tensinl protein in GC tissues and adjacent normal tissues mainly expressed in cytoplasm.Of 163 patients,154 (66 with high expression and 88 with low expression) and 9 had respectively positive and negative expressions of Tensinl protein in GC tissues;79 (37 with high expression and 42 with low expression) and 84 had respectively positive and negative expressions of Tensinl protein in adjacent normal tissues,with statistically significant differences in positive expression ratio and expression levels (x2=64.65,12.93,P＜0.05).(2) Association between expression of Tensinl protein in GC tissues and clinicopathological characteristics:high expression rate of Tensinl protein in GC tissues were respectively 31.34％ (21/67) in GC patients with tumor metastases and 46.88％ (45/96) in GC patients without tumor metastasis,with a statistically significant difference (x2 =3.95,P＜0.05).(3) Follow-up and survival situations:all the 163 patients were followed up for 3.3-64.7 months,with a median time of 28.7 months.The 3-year cumulative disease-free survival rate and cumulative overall survival rate in GC tissues were 63.12％,74.22％ in 66 patients with high expression of Tensinl protein and 47.30％,55.74％ in 97 patients with low and negative expressions of Tensin1 protein,showing statistically significant differences in above indicators (x2 =4.58,4.11,P＜0.05).Survival analysis of subgroups showed that 3-year cumulative disease-free survival rate in GC tissues of patients with maximum tumor dimension ≥ 5 cm,nerve and / or vascular invasions and stage Ⅲ of TNM staging were 45.98％,62.79％,52.75％ in patients with high expression of Tensin1 protein and 18.11％,31.10％,32.80％ in patients with low and negative expressions of Tensin1 protein,with a statistically significant difference (x2 =5.85,7.89,4.96,P＜0.05).The 3-year cumulative overall survival rate was respectively 66.00％,75.75％,67.93％ in patients with high expression of Tensin1 protein and 30.74％,40.15％,44.67％ in patients with low and negative expressions of Tensinl protein,with statistically significant differences (x2 =7.59,9.62,4.32,P ＜ 0.05).(4) Prognostic factors analysis:results of univariate analysis showed that maximum tumor dimension,histological grade,nerve and / or vascular invasions,postoperative TNM staging,postoperative adjuvant chemotherapy and expression of Tensin1 protein were related factors affecting prognoses of GC patients [hazard ratio (HR) =3.66,2.45,2.17,3.36,0.41,0.54,95％ confidence interval (CI):2.09-6.41,1.43-4.19,1.17-4.04,1.52-7.41,0.23-0.72,0.31-0.96,P＜0.05].Results of multivariate analysis showed that maximum tumor dimension ≥ 5 cm and grade Ⅲ of histological grade were independent risk factors affecting prognoses of GC patients (HR=3.21,2.17,95％CI:1.63-6.32,1.18-3.99,P＜0.05),and postoperative adjuvant chemotherapy and high expression of Tensin1 protein were independent protective factors affecting prognoses of GC patients (HR=0.50,0.44,95％CI:0.28-0.90,0.24-0.82,P＜0.05).Conclusion High expression of Tensin1 protein may inhibit GC metastasis,and it is also an independent protective factor affecting prognoses of GC patients.

The crystal structure and biochemical properties of DHBPS from Streptococcus pneumoniae, a potential anti-infective target for Gram-positive bacteria.

The enzymes involved in riboflavin biosynthesis are considered to be potential anti-bacterial drug targets because these proteins are essential in bacterial pathogens but are absent in humans. 3,4-dihydroxy-2-butanone-4-phosphate synthase (DHBPS) is one of the key enzymes in the biosynthesis of riboflavin. DHBPS catalyzes the conversion of ribulose-5-phosphate (Ru5P) to 3,4-Dihydroxy-2-butanone-4-phosphate (DHBP) and formate. The purified SpDHBPS enzyme, in the presence of Mg(2+) ion, catalyzed the conversion of Ru5P to DHBP at a rate of 109nmolmin(-1)mg(-1) with an apparent Km value of 181µM at 37°C. Surprisingly, our experiments first revealed that DHBPS showed activity in the presence of the trivalent metal ion, Fe(3+). Furthermore, we determined the crystal structure of DHBPS from Gram-positive bacteria, Streptococcus pneumoniae, with 2.0Å resolution. The overall architecture of SpDHBPS was similar to its homologs, which comprise one ß-sheet (five-stranded) and eight α-helices, adopting a three-layered α-ß-α sandwich fold. Similar to the homologs, gel-filtration experiments verified that the enzyme was arranged as a dimer. Although the overall fold of DHBPS was similar, the significant structural differences between the species at the active site region may be utilized to develop antibacterial agents that are species-specific.

Studies on expression, purification, crystal growth and optimization of putative transcription factor LytR from Streptococcus pneumoniae / 生物医学工程学杂志

The aim of the present study was to obtain the crystal of transcription factor LytR of streptococcus pneumoniae for X-ray crystal structure and function analysis. The LytR gene of D39 strains from Streptococcus pneumoniae (S. pn) was cloned into the prokaryotic expression vector pET32a(+), then overexpression was obtained in the E. coli BL21 (DE3) through transformation of the recombinant plasmid that had been verified by colony PCR and sequencing. Soluble fusion protein with His-tag highly expressed by the induction of 0.5 mmol/L IPTG and was purified by a three step procedure, the purity of the purified LytR recombinant protein was over 90%. Preliminary screening of crystallization conditions was performed using the hanging-drop vapour-diffusing method with Hampton Crystal screen and PEG screen kits. The protein crystals X-ray diffraction data were collected from a single crystal and more stick crystals whose X-ray diffraction reached 4.0 A were obtained. These works laid the foundation for further research on the 3D structure of putative transcription factor LytR and its biological aspects.

Processing and Exploration of the Bioinformatics Course / 中华医学教育探索杂志

Bioinformatics is a new field of biomedical science which based on biological,information technology to storage,retrieval and analysis the biological data.This emerging subject is important for the improvements of scientific ideas and ability of biomedical graduate students.Based on the medical background and future study of the graduate students,it is a key point that how to performing the teaching work in accordance with the student's aptitude.To promote the level of bioinformatics course and enrich the theory knowledge and ability of practice of the medical graduate students,we discuss three relate issues such as the content of courses,teaching term and teaching model in this paper.