Laboratory Diagnosis and Monitoring the Viral Shedding of SARS-CoV-2 Infection

The worldwide epidemic of coronavirus disease 2019 (COVID-19) is ongoing. Rapid and accurate detection of the causative virus SARS-CoV-2 is vital for the treatment and control of COVID-19. In this study, the comparative sensitivity of different respiratory specimen types were retrospectively analyzed using 3,552 clinical samples from 410 COVID-19 patients confirmed by Guangdong CDC (Center for Disease Control and Prevention). Except for bronchoalveolar lavage fluid (BALF), the sputum possessed the highest positive rate (73.4%-87.5%), followed by nasal swabs (53.1%-85.3%) for both severe and mild cases during the first 14 days after illness onset (d.a.o.). Viral RNA could be detected in all BALF samples collected from the severe group within 14 d.a.o. and lasted up to 46 d.a.o. Moreover, although viral RNA was negative in the upper respiratory samples, it was also positive in BALF samples in most cases from the severe group during treatment. Notably, no viral RNA was detected in BALF samples from the mild group. Despite typical ground-glass opacity observed via computed tomographic scans, no viral RNA was detected in the first three or all upper respiratory tract specimens from some COVID-19 patients. In conclusion, sputum is most sensitive for routine laboratory diagnosis of COVID-19, followed by nasal swabs. Detection of viral RNA in BALF improves diagnostic accuracy in severe COVID-19 patients.

Laboratory Diagnosis and Monitoring the Viral Shedding of SARS-CoV-2 Infection

The worldwide epidemic of coronavirus disease 2019 (COVID-19) is ongoing. Rapid and accurate detection of the causative virus SARS-CoV-2 is vital for the treatment and control of COVID-19. In this study, the comparative sensitivity of different respiratory specimen types were retrospectively analyzed using 3,552 clinical samples from 410 COVID-19 patients confirmed by Guangdong CDC (Center for Disease Control and Prevention). Except for bronchoalveolar lavage fluid (BALF), the sputum possessed the highest positive rate (73.4%-87.5%), followed by nasal swabs (53.1%-85.3%) for both severe and mild cases during the first 14 days after illness onset (d.a.o.). Viral RNA could be detected in all BALF samples collected from the severe group within 14 d.a.o. and lasted up to 46 d.a.o. Moreover, although viral RNA was negative in the upper respiratory samples, it was also positive in BALF samples in most cases from the severe group during treatment. Notably, no viral RNA was detected in BALF samples from the mild group. Despite typical ground-glass opacity observed via computed tomographic scans, no viral RNA was detected in the first three or all upper respiratory tract specimens from some COVID-19 patients. In conclusion, sputum is most sensitive for routine laboratory diagnosis of COVID-19, followed by nasal swabs. Detection of viral RNA in BALF improves diagnostic accuracy in severe COVID-19 patients.

What troponin I level post PCI in SIHD is predictive of higher risk of MACE?

Background

According to the 4th universal definition of myocardial infarction (MI), post percutaneous coronary intervention (PCI) MI is defined as an elevation of cardiac troponin values more than five times above the 99th percentile upper reference limit. The ISCHEMIA Trial in stable ischaemic heart disease (SIHD) patients reported post PCI troponin rise as part of the primary endpoint. What represents a clinically significant troponin rise post PCI has not been clearly established.

Purpose

The aim of our study was to correlate the level of troponin I rise with adverse events post PCI in SIHD.

Methods

We performed a retrospective analysis of our PCI registry in patients with SIHD between 2014 and 2018. Patients with acute coronary syndrome were excluded. HS-troponin I was measured one day after the procedure. The primary end point was major adverse cardiac events (MACE) including death, MI, stent thrombosis (ST) and need for repeat revascularization within 12 months from index procedure.

Results

Between 2014 and 2018, 920 patients (mean age 67.5 years, 78% male) underwent PCI for SIHD. Troponin rise post PCI was a common event and a level more than 100ng/L (reference range <26 ng/L) occurred in 54% of patients. Mean and median troponin I level post PCI was 675 ng/L±2530 and 118 ng/L respectively. In patients with MACE, mean troponin I level was 1361 ng/L compared with 611 ng/L in patients without MACE (P=0.0176). Correlation of troponin I level with one year MACE rates are shown in the Graph. MACE rates were steady at 8.5% with troponin I levels below 2500 ng/L after which there was a significant increase in the MACE rates. At troponin I level above 5000 ng/L MACE was 13.6% and above 10,000 ng/L it was 33.3%.

Conclusion

Troponin I levels above 2500 ng/L (x100 upper limit normal) correlated with an increase in the risk of MACE in patients undergoing PCI for SIHD. Our results suggest that current definitions of procedural MI overestimate the clinical significance of post PCI troponin rise.

Funding Acknowledgement

Type of funding source: None

Optimization of GRACE risk stratification by NT-proBNP combined with D-dimer in patients with non-ST-elevation myocardial infarction

Background

GRACE risk score is the most widely used tool to predict the risk of death and myocardial infarction in patients with Non-ST-elevation myocardial infarction (NSTEMI). Some biomarkers have been shown to have a high predictive value for prognosis. But the models constructed using these studies have some drawbacks, including the using biomarkers that are not routinely monitored.

Aims

To explore the optimizing role of multiple biomarkers in GRACE risk stratification in NSTEMI and then develop a new scoring system based on GRACE.

Methods

1.This multi-center, prospective, cohort study enrolled 1357 patients (mean age 65±12 years; 57% male). Common clinical indicators were collected within the first 12h after admission. 2.The outcome was 1-year all-cause mortality and major adverse cardiac events (MACE: all-cause death,unstable angina, heart failure, recurrent myocardial infarction and stroke). 3.Cox multivariate anlysis was used to quantify the biomarker effect. C-index, NRI and IDI were calculated to verify that the biomarkers improve the predictive accuracy of GRACE.

Results

1. During follow-up (mean: 339 days), 57 participants died and 211 participants had 231 MACE. In COX analysis, NT-proBNP (P<0.0001), and d-dimer (P=0.0092) were significant independent biomarkers for death. NT-proBNP (P<0.0001), fibrinogen (P=0.0177) and d-dimer (P<0.0001) were significant independent biomarkers for MACE. 2. For all-cause death, the combination of NT-proBNP and D-dimer improved the predictive accuracy of GRACE the most. For MACE, trigeminal combination of NT-proBNP, fibrinogen, and D-dimer improved GRACE the most 3. NT-proBNP, D-dimer, fibrinogen, and GRACE comprise a new scoring system for assessing 1-year clinical events. Kaplan-Meier analysis revealed a significant rise in 1-year mortality and MACE between different score groups.

Conclusions

The combination of NT-proBNP, and d-dimer added the prognostic value of GRACE for all-cause death and MACE. Our newly developed scoring system can be easily calculated in clinical practice and strongly correlated with all-cause mortality and MACE.

Risk score and survival curve

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Major Science and Technology Projects of Tianjin Science and Technology Commission in 2016; Key Project of Healthcare Industry of Tianjin in 2016

The differential immune responses to COVID-19 in peripheral and lung revealed by single-cell RNA sequencing

Understanding the mechanism that leads to immune dysfunction in severe coronavirus disease 2019 (COVID-19) is crucial for the development of effective treatment. Here, using single-cell RNA sequencing, we characterized the peripheral blood mononuclear cells (PBMCs) from uninfected controls and COVID-19 patients and cells in paired broncho-alveolar lavage fluid (BALF). We found a close association of decreased dendritic cells (DCs) and increased monocytes resembling myeloid-derived suppressor cells (MDSCs), which correlated with lymphopenia and inflammation in the blood of severe COVID-19 patients. Those MDSC-like monocytes were immune-paralyzed. In contrast, monocyte-macrophages in BALFs of COVID-19 patients produced massive amounts of cytokines and chemokines, but secreted little interferons. The frequencies of peripheral T cells and NK cells were significantly decreased in severe COVID-19 patients, especially for innate-like T and various CD8+ T cell subsets, compared to healthy controls. In contrast, the proportions of various activated CD4+ T cell subsets among the T cell compartment, including Th1, Th2, and Th17-like cells were increased and more clonally expanded in severe COVID-19 patients. Patients' peripheral T cells showed no sign of exhaustion or augmented cell death, whereas T cells in BALFs produced higher levels of IFNG, TNF, CCL4, CCL5, etc. Paired TCR tracking indicated abundant recruitment of peripheral T cells to the severe patients' lung. Together, this study comprehensively depicts how the immune cell landscape is perturbed in severe COVID-19.

X-ray attenuation models to account for beam hardening in computed tomography

We introduce a beam-hardening correction method for lab-based X-ray computed tomography (CT) by modifying existing iterative tomographic reconstruction algorithms. Our method simplifies the standard Alvarez-Macovski X-ray attenuation model [Phys. Med. Biol.21, 733 (1976)] and is compatible with conventional (i.e., single-spectrum) CT scans. The sole modification involves a polychromatic projection operation, which is equivalent to applying a weighting that more closely matches the attenuation of polychromatic X-rays. Practicality is a priority, so we only require information about the X-ray spectrum and some constants relating to material properties. No other changes to the experimental setup or the iterative algorithms are necessary. Using reconstructions of simulations and several large experimental datasets, we show that this method is able to remove or reduce cupping, streaking, and other artefacts from X-ray beam hardening and improve the self-consistency of projected attenuation in CT. When the assumptions made in the simplifications are valid, the reconstructed tomogram can even be quantitative.

LncRNA AOC4P affects biological behavior of gastric cancer cells through MAPK signaling pathway

OBJECTIVE

Long non-coding RNA (lncRNA) is closely related to the occurrence and development of gastric cancer, but the mechanism and clinical significance of lncRNA AOC4P are still unclear. This study aimed to investigate the expression and function of lncRNA AOC4P in gastric cancer.

PATIENTS AND METHODS

Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was used to detect the expression of lncRNA AOC4P in 80 gastric cancer tissues and adjacent normal tissues. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide), flow cytometry and transwell assays were used to study the effects of lncRNA AOC4P on the proliferation, apoptosis, migration and invasion of gastric cancer cells. Western blot was used to detect the related protein level of the mitogen-activated protein kinase (MAPK) signal pathway.

RESULTS

The expression of lncRNA AOC4P in gastric cancer tissues was higher than that in adjacent tissues. OS or DFS time were significantly shortened in patients with gastric cancer with high expression of lncRNA AOC4P. Inhibition of lncRNA AOC4P expression can inhibit cell proliferation, migration and invasion, promoting cell apoptosis to some extent. Inhibition of lncRNA AOC4P expression also can result in the decreased expression levels of extracellular-signal-regulated kinase 1 (ERK1), c-Jun N-terminal kinases (JNK) and p38 proteins.

CONCLUSIONS

High expression of lncRNA AOC4P in gastric cancer may be related to the occurrence, development and prognosis of gastric cancer. LncRNA AOC4P is expected to become a new diagnostic marker and therapeutic target for gastric cancer.

Denitrosylation of nNOS induced by cerebral ischemia-reperfusion contributes to nitrosylation of CaMKII and its inhibition of autophosphorylation in hippocampal CA1

OBJECTIVE

The aim of this study is to investigate the relation between CaMKII S-nitrosylation and its activation, as well as the underlying mechanism, after global cerebral ischemia-reperfusion.

MATERIALS AND METHODS

The rat model of cerebral ischemia-reperfusion was established by four-vessel occlusion of 15 min and reperfusion of different times. nNOS inhibitor 7-nitroindazole (7-NI), exogenous nitric oxide donor GSNO (nitrosoglutathione), or N-methyl-D-aspartate receptor (NMDAR) antagonist MK-801 were administered before ischemia. The expressions of S-nitrosylation and phosphorylation of CaMKII and nNOS were detected by biotin switch assay, immunoblotting, and immunohistochemical staining after cerebral ischemia-reperfusion. The survival of hippocampal CA1 pyramidal cells after administration of the three drugs was examined by cresyl violet staining.

RESULTS

Following cerebral ischemia-reperfusion, the S-nitrosylation of CaMKII was increased, accompanied by a decrease of phosphorylation, suggesting a decrease of activity (p<0.05). Meanwhile, the phosphorylation and S-nitrosylation of nNOS were notably decreased at the same time point (p<0.05). The administration of 7-NI, GSNO, and MK-801 increased the S-nitrosylation and phosphorylation of nNOS, leading to the attenuation of increased S-nitrosylation and decreased autophosphorylation of CaMKII after cerebral ischemia-reperfusion (p<0.05). Administration of MK-801, GSNO, and 7-NI significantly decreased the neuronal damage in rat hippocampal CA1 caused by cerebral ischemia-reperfusion (p<0.05).

CONCLUSIONS

After cerebral ischemia-reperfusion, the decrease of autophosphorylation of CaMKII regulated by its S-nitrosylation may be due to the denitrosylation of nNOS and subsequent NO production. Increasing the phosphorylation of CaMKII by nNOS inhibitor, exogenous NO donor or NMDA receptor antagonist exerted neuroprotective effects against cerebral ischemia-reperfusion injury.

Replacing true unenhanced imaging in renal carcinoma with virtual unenhanced images in dual-energy spectral CT: a feasibility study

AIM

To investigate the clinical value of virtual unenhanced (VNC) spectral computed tomography (CT) images to replace the conventional true unenhanced spectral CT images (TNC) in diagnosing renal carcinoma.

MATERIALS AND METHODS

Fifty-six cases of renal carcinoma confirmed by histopathology underwent conventional plain CT and contrast-enhanced spectral CT at arterial phase (AP) and venous phase (VP). VNC images were generated on an AW4.6 workstation. The CT attenuation, image noise, contrast-to-noise ratio (CNR), and signal-noise-ratio (SNR) of the renal lesions and normal kidneys, long and short axis diameters of the lesion were measured from the three image sets and analysed using one-way analysis of variance (ANOVA). Two radiologists evaluated image quality subjectively using a five-point score, and lesion signature using a three-point score. Image quality scores were compared statistically and tested for consistency.

RESULTS

The two reviewers had good agreement for subjective evaluation (Kappa>0.70) and there was no difference in the quality of the scores among the three image groups. The lesion signature scores were all above the acceptable level. The CNR and SNR values in VNC were significantly higher than in TNC (p<0.05). VNC images had lower renal noise than in TNC (p<0.05). There was no difference in the long and short axis diameters of the lesion among the three image groups. VNC had higher CT attenuation values for the lesion and kidney than TNC (p<0.05), but the differences were <5 HU.

CONCLUSION

VNC images in spectral CT may be used to replace the conventional plain CT to reduce imaging duration and radiation dose in diagnosing renal carcinoma.

The prokaryotic expression, polyclonal antibody preparation, and subcellular localization of the transmembrane protein NS2A of the duck Tembusu virus

Duck Tembusu virus (DTMUV) is a single-stranded, positive-sense RNA arbovirus, belonging to the genus Flavivirus, the family Flaviviridae. As a transmembrane protein, non-structural protein 2A (NS2A) plays an important role in virion assembly, replication complex and antagonizing host immune response. Since NS2A protein contains many hydrophobic amino acids, it is hard to gain the full-length protein of NS2A for prokaryotic expression. Therefore, to make a deep study, prokaryotic expression and polyclonal antibody preparation of truncated DTMUV NS2A was performed. The truncated NS2A gene (178-450 bp) was obtained, and sub-cloned into the prokaryotic vector pGEX-4T-1 (pGEX-4T-1-NS2A178-450bp). Subsequently, the recombinant GST-NS2A60-150aa protein was successfully expressed in E. coli BL21 (DE3) with the induction by 0.3 mmol/l isopropyl β-D-thiogalactoside (IPTG) for 6 h at 37°C. The GST-NS2A60-150aa protein was extracted from the gel. The BALB/c mice were immunized with the purified recombinant NS2A protein to prepare polyclonal antibodies against the truncated NS2A protein. The titer of the polyclonal antibodies, determined by ELISA analysis, was 1:128,000. The specificity of the polyclonal antibodies (mPAb-DTMUV-NS2A60-150aa) were verified by Western blot analysis. Furthermore, the indirect immunofluorescence (IFA) was performed to explore the subcellular localization of NS2A. NS2A protein was, in the transfected cells, located mainly around nucleus in the endoplasmatic reticulum. Taken together, our study provided a useful tool for the further exploration of the biological functions and molecular mechanism of DTMUV NS2A. Keywords: duck Tembusu virus; non-structural protein 2A; prokaryotic expression; polyclonal antibodies; subcellular location.

LncRNA CASC19 promotes the proliferation, migration and invasion of non-small cell lung carcinoma via regulating miRNA-130b-3p

OBJECTIVE

To uncover the biological role of long non-coding RNA (lncRNA) CASC19 in the pathogenesis of non-small cell lung carcinoma (NSCLC) and the potential mechanism.

PATIENTS AND METHODS

Expression pattern of lncRNA CASC19 in NSCLC tissues and cell lines was determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Survival analysis on the correlation between CASC19 level and prognosis of NSCLC patients was conducted by introducing for the Kaplan-Meier estimator. After the transfection of si-CASC19 in A549 and PC9 cells, changes in viability, migratory, and invasive capacities were evaluated. Dual-luciferase reporter gene assay was performed to explore the interaction between microRNA-130b-3p (miRNA-130b-3p) and CASC19/ZEB2. Their interactive effects on the progression of NSCLC were finally investigated through rescue experiments.

RESULTS

LncRNA CASC19 was upregulated in NSCLC tissues and cell lines. NSCLC patients with high expression of CASC19 presented a worse survival. Knockdown of CASC19 attenuated proliferative, migratory, and invasive capacities of A549 and PC9 cells. CASC19 sponged miRNA-130b-3p and negatively regulated its level. ZEB2 was the direct target of miRNA-130b-3p. The knockdown of miRNA-130b-3p reversed the regulatory effects of CASC19 on A549 and PC9 cells.

CONCLUSIONS

CASC19 sponges miRNA-130b-3p to regulate ZBR2 as a ceRNA, thus accelerating the progression of NSCLC by regulating proliferative, migratory, and invasive capacities of tumor cells.

[Quantitative measurement of cross-sectional area of small pulmonary vessels in pulmonary embolism]

Objective: The relationship between the percentage of total cross-sectional area (% CSA) of small pulmonary vessels for the lung area in CTPA and the right ventricular function parameters in patients with pulmonary embolism. Methods: 120 patients with PE and 72 healthy subjects underwent CTPA and all date were analyzed Retrospectively. The main pulmonary artery diameter (mPA), the ratio of the main pulmonary artery to the ascending aorta diameter (rPA), right ventricle/left ventricular diameter ratio (RVd/LVd), and the pulmonary artery obstruction index (PAOI) in the PE group were measured for all subjects. The %CSA<5 mm(2) and 5-10 mm(2) for the lung area (%CSA(<5) and %CSA(5-10)) of small pulmonary vessels were measured with Image J image-processing program. According to the risk stratification of the 2018 Guidelines for the Diagnosis and Treatment of Pulmonary Thromboembolism, PE patients were divided into medium-high risk group (RVd/LVd>1) and low-risk group (RVd/LVd<1). The indexes of PE in medium-high risk group, low risk group and control group were compared by ANOVA, and the indexes among PE subgroups were compared by independent sample t-test. Spearman correlation method was used to analyze the correlation between %CSA and right ventricular function parameters of PE patients. Results: %CSA(<5) of medium-high risk group, low-risk group and control group were (0.69±0.19)%, (0.95±0.27)% and (0.99±0.30)% (P<0.01), respectively. %CSA(5-10) of three groups were (0.63±0.15)%, (0.84±0.18)%, and (0.85±0.25)% (P<0.01), respectively; %CSA(<5) and %CSA(5-10) of medium-high risk group were lower than low-risk group and control group. %CSA(<5) and %CSA(5-10) in PE patients correlated negatively with RVd/LVd, rPA and mPA (r=-0.545/-0.549, -0.235/-0.352, -0.239/-0.298, respectively). Conclusion: The measurement of % CSA<(5) and %CSA (5-10) in CTPA were negatively correlated with RVd/LVd in patients with pulmonary embolism, which indirectly reflected the severity of the pulmonary embolism patients.

Antimicrobial resistance phenotypes and genotypes of Streptococcus suis isolated from clinically healthy pigs from 2017 to 2019 in Jiangxi Province, China

AIMS

This study aimed to investigate the antimicrobial resistance (AMR) profiles and genotypes of Streptococcus suis from Jiangxi Province, China.

METHODS AND RESULTS

A total of 314 nasal swab samples were collected from clinically healthy pigs, with a positive isolation rate of S. suis of 34·08%. Antimicrobial susceptibility testing showed that more than 80% of the isolates were susceptible to vancomycin, penicillin, minocycline and chloramphenicol. A high frequency of resistance to clindamycin, tetracycline, clarithromycin and erythromycin was observed. All of the isolates were resistant to three or more categories of antimicrobials. The erm(B) and tet(O) served as the most frequent genotypes that contributed to lincosamide, macrolide and tetracycline resistances. A part of macrolide-resistant genotypes could not exhibit specific phenotypes. Finally, integrative and conjugative elements (ICEs) were identified in 28·97% of the isolates.

CONCLUSIONS

The multidrug resistance of S. suis has widely emerged in Jiangxi Province. The most prevalent resistance genes and genotypes were similar to those in other regions or countries. The presence of ICEs is increasing the risk of horizontal transfer of AMR genes.

SIGNIFICANCE AND IMPACT OF THE STUDY

The findings could provide guidance for the rational use of antimicrobial drugs and be helpful for monitoring the AMR information of S. suis in China.

[A preliminary study on the evaluation of diaphragm function by ultrasound in patients with invasive mechanical ventilation]

Objectives: To study the feasibility of using ultrasound to evaluate diaphragm function in patients with invasive mechanical ventilation. Methods: From March to December 2017, 40 adult patients with acute respiratory distress syndrome who were admitted to the Department of Critical Care Medicine, Xiangya Hospital, Central South University for more than 48 hours were included. Diaphragmatic excursion and thickness of bilateral anterior, middle and posterior parts were measured by ultrasound for 5 consecutive days. Results: (1) Compared with the diaphragmatic excursion of the right [anterior: (11.05±3.04) mm; middle: (12.08±2.71) mm; posterior: (11.51±3.33) mm] and left [anterior: (13.63±7.52) mm; middle: (15.44±7.52) mm; posterior: (14.76±6.93) mm] sides on day 1, the diaphragmatic excursion of the right [anterior: (8.90±3.65) mm; middle: (10.02±4.24) mm; posterior: (10.25±4.38) mm] and left [anterior: (9.82±1.96) mm; middle: (11.60±1.13) mm; posterior: (11.52±1.98) mm] sides decreased significantly on day 3 (P<0.05). Bilateral anterior, middle and posterior diaphragmatic excursion recovered on day 5, and was higher than the baseline levels on day 1, with the left middle and posterior diaphragmatic excursion changing most significantly. (2) Compared with day 1, 2, 3, the thickening fraction of bilateral anterior, middle and posterior diaphragm were significantly decreased on day 4, with the left middle part [day 1: (33.87±14.34)%; day 2: (37.26±13.91)%; day 3: (30.56±14.27)%; day 4: (15.53±5.68)%] and the left posterior part [day 1: (35.50±15.69)%; day 2: (39.84±15.32)%; day 3: (29.06±14.96)%; day 4: (13.30±5.79)%] changing most significantly (P<0.05). The thickening fractions of left anterior, middle and posterior diaphragm recovered on day 5 compared with that on day 4, but still lower than those on day 1 (P<0.05). Conclusions: It is feasible to evaluate the diaphragm function in patients with invasive mechanical ventilation by ultrasound, which can provide guidance for preventing diaphragmatic atrophy and withdrawing from mechanical ventilation.