Recent developments and trends of automatic nucleic acid detection systems.

Nucleic acid detection, widely used in clinical diagnosis, biological analysis, and environmental monitoring, is of great significance for disease diagnosis and basic research. With the outbreak of COVID-19, the demand for fast and high-throughput nucleic acid detection from large numbers of samples has increased sharply. Automated nucleic acid detection systems can meet these needs, and also play important roles in disease screening and infectious disease prevention and control. In this review, we introduce and compare the current mainstream nucleic acid automatic detection instruments and equipment, then discuss the future demands of nucleic acid detection.

A Novel Strategy for Rapid Fluorescence Detection of FluB and SARS-CoV-2

Undoubtedly, SARS-CoV-2 has caused an outbreak of pneumonia that evolved into a worldwide pandemic. The confusion of early symptoms of the SARS-CoV-2 infection with other respiratory virus infections made it very difficult to block its spread, leading to the expansion of the outbreak and an unreasonable demand for medical resource allocation. The traditional immunochromatographic test strip (ICTS) can detect one analyte with one sample. Herein, this study presents a novel strategy for the simultaneous rapid detection of FluB/SARS-CoV-2, including quantum dot fluorescent microspheres (QDFM) ICTS and a supporting device. The ICTS could be applied to realize simultaneous detection of FluB and SARS-CoV-2 with one test in a short time. A device supporting FluB/SARS-CoV-2 QDFM ICTS was designed and had the characteristics of being safe, portable, low-cost, relatively stable, and easy to use, ensuring the device could replace the immunofluorescence analyzer in cases where there is no need for quantification. This device does not need to be operated by professional and technical personnel and has commercial application potential.

A Novel Strategy for Rapid Fluorescence Detection of FluB and SARS-CoV-2.

Undoubtedly, SARS-CoV-2 has caused an outbreak of pneumonia that evolved into a worldwide pandemic. The confusion of early symptoms of the SARS-CoV-2 infection with other respiratory virus infections made it very difficult to block its spread, leading to the expansion of the outbreak and an unreasonable demand for medical resource allocation. The traditional immunochromatographic test strip (ICTS) can detect one analyte with one sample. Herein, this study presents a novel strategy for the simultaneous rapid detection of FluB/SARS-CoV-2, including quantum dot fluorescent microspheres (QDFM) ICTS and a supporting device. The ICTS could be applied to realize simultaneous detection of FluB and SARS-CoV-2 with one test in a short time. A device supporting FluB/SARS-CoV-2 QDFM ICTS was designed and had the characteristics of being safe, portable, low-cost, relatively stable, and easy to use, ensuring the device could replace the immunofluorescence analyzer in cases where there is no need for quantification. This device does not need to be operated by professional and technical personnel and has commercial application potential.

Elucidation of Binding Features and Dissociation Pathways of Inhibitors and Modulators in SARS-CoV-2 Main Protease by Multiple Molecular Dynamics Simulations.

COVID-19 can cause different neurological symptoms in some people, including smell, inability to taste, dizziness, confusion, delirium, seizures, stroke, etc. Owing to the issue of vaccine effectiveness, update and coverage, we still need one or more diversified strategies as the backstop to manage illness. Characterizing the structural basis of ligand recognition in the main protease (Mpro) of SARS-CoV-2 will facilitate its rational design and development of potential drug candidates with high affinity and selectivity against COVID-19. Up to date, covalent-, non-covalent inhibitors and allosteric modulators have been reported to bind to different active sites of Mpro. In the present work, we applied the molecular dynamics (MD) simulations to systematically characterize the potential binding features of catalytic active site and allosteric binding sites in Mpro using a dataset of 163 3D structures of Mpro-inhibitor complexes, in which our results are consistent with the current studies. In addition, umbrella sampling (US) simulations were used to explore the dissociation processes of substrate pathway and allosteric pathway. All the information provided new insights into the protein features of Mpro and will facilitate its rational drug design for COVID-19.

Pathways from self-disclosure to medical coping strategy among adolescents with moderate and major depression during the COVID-19 pandemic: A mediation of self-efficacy

Background The prevalence of adolescent depression in China during the COVID-19 pandemic is increasing. Self-disclosing depressive emotions could help release stress. Self-disclosure, which is a prerequisite for self-efficacy, can directly contribute to people’s psychological health, and depression and the choice of coping strategy are determined by the level of self-efficacy perceived. Purpose We aimed to discuss the relationship between self-efficacy, self-disclosure, and medical coping strategy. Further, we explore the mediation effect of self-efficacy on the influence of self-disclosure on medical coping strategies in adolescents with depression. Methods A total of 585 patients aged 11–24 years with moderate and major depression were recruited. All the assessments were completed on the second day after admission, including the General Self-Efficacy Scale (GSE), Distress Disclosure Index (DDI), and Medical Coping Modes Questionnaire (MCMQ). Pearson correlation was performed to explore the relationships of these variables. The bootstrap analysis was used to conduct to assess the mediation effects. Results Both direct and indirect effects of self-disclosure on medical coping strategy were found. As predicted, self-efficacy partially mediated the relationship between self-disclosure and medical coping strategy (b = 0.0385, 95% CI: 0.0244–0.0538 for Confrontation;b = –0.0466, 95%CI: –0.0651 to –0.0296 for Resignation), respectively. The effect size for Confrontation and Resignation was 0.2659 and 0.2485, respectively. Conclusion Self-efficacy played a partial mediating role in the effect of self-disclosure on medical coping strategies for adolescent depression during the COVID-19 pandemic, and the use of a positive self-disclosure mechanism may be anticipated to promote improved self-efficacy and the use of active coping strategies.

Clinical characteristics of patients with confirmed and asymptomatic SARS-CoV-2 infection in China.

OBJECTIVE: To examine the clinical characteristics of patients with asymptomatic novel coronavirus disease 2019 (COVID-19) and compare them with those of patients with mild disease. DESIGN: A retrospective cohort study. SETTING: Multiple medical centers in Wuhan, Hubei, China. PARTICIPANTS: A total of 3,263 patients with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection between February 4, 2020, and April 15, 2020. MAIN OUTCOME MEASURES: Patient demographic characteristics, medical history, vital signs, and laboratory and chest computed tomography (CT) findings. RESULTS: A total of 3,173 and 90 patients with mild and moderate, and asymptomatic COVID-19, respectively, were included. A total of 575 (18.2%) symptomatic patients and 4 (4.4%) asymptomatic patients developed the severe illness. All asymptomatic patients recovered; no deaths were observed in this group. The median duration of viral shedding in asymptomatic patients was 17 (interquartile range, 9.25-25) days. Patients with higher levels of ultrasensitive C-reactive protein (odds ratio [OR] = 1.025, 95% confidence interval [CI], 1.01-1.04), lower red blood cell volume distribution width (OR = 0.68, 95% CI 0.51-0.88), lower creatine kinase Isoenzyme(0.94, 0.89-0.98) levels, or lower lesion ratio (OR = 0.01, 95% CI 0.00-0.33) at admission were more likely than their counterparts to have asymptomatic disease. CONCLUSIONS: Patients with younger ages and fewer comorbidities are more likely to be asymptomatic. Asymptomatic patients had similar laboratory characteristics and longer virus shedding time than symptomatic patients; screen and isolation during their infection were helpful to reduce the risk of SARS-CoV-2 transmission.

Semiformal Organizations and Control During the COVID-19 Crisis in China.

Scholars often compare China and Western societies in terms of dichotomous forms of control-formal and informal. Recent research indicates a nuanced form of social control-semiformal. Using a survey data collected during the 2020 COVID-19 pandemic in China, this study investigated the prevalence and importance of semiformal organizations, formal organizations, and informal groups participating in social control and social service and the predictors of the perceived importance of these three forms of social control mechanisms. Findings from this study revealed that formal organizations, the semiformal organizations, and informal groups all participated in community control and service. Semiformal organizations had the highest level of participation. This study found that education and age are the two major predictors of the views on the importance of formal, informal, and semiformal control and control mechanisms.

Mycotoxins in Maize Silage from China in 2019.

Animal feed (including forage and silage) can be contaminated with mycotoxins. Here, 200 maize silage samples from around China were collected in 2019 and analyzed for regulated mycotoxins, masked mycotoxins (deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, and deoxynivalenol-3-glucoside), and emerging mycotoxins (beauvericin, enniatins, moniliformin, and alternariol). Deoxynivalenol and zearalenone were detected in 99.5% and 79.5% of the samples, respectively. Other regulated mycotoxins were detected in fewer samples. The highest deoxynivalenol and zearalenone concentrations were 3600 and 830 µg/kg, respectively. The most commonly detected masked mycotoxin was 15-acetyldeoxynivalenol, which was detected in 68.5% of the samples and had median and maximum concentrations of 61.3 and 410 µg/kg, respectively. The emerging mycotoxins beauvericin, alternariol, enniatin A, enniatin B1, and moniliformin were detected in 99.5%, 85%, 80.5%, 72.5%, and 44.5%, respectively, of the samples but at low concentrations (medians <25 µg/kg). The samples tended to contain multiple mycotoxins, e.g., the correlation coefficients for the relationships between the concentrations of beauvericin and deoxynivalenol, deoxynivalenol and zearalenone, and zearalenone and beauvericin were 1.0, 0.995, and 0.995, respectively. The results indicated that there needs to be more awareness of the presence of one or more masked and emerging mycotoxins in maize silage in China.

Recent developments and trends of automatic nucleic acid detection systems

Nucleic acid detection, widely used in clinical diagnosis, biological analysis, and environmental monitoring, is of great significance for disease diagnosis and basic research. With the outbreak of COVID-19, the demand for fast and high-throughput nucleic acid detection from large numbers of samples has increased sharply. Automated nucleic acid detection systems can meet these needs, and also play important roles in disease screening and infectious disease prevention and control. In this review, we introduce and compare the current mainstream nucleic acid automatic detection instruments and equipment, then discuss the future demands of nucleic acid detection.

Emerging optofluidic technologies for biodiagnostic applications

The unprecedented global COVID‐19 pandemic strongly argues the critical need for innovative diagnostic tools meeting the requirement of test speed, accuracy, and throughput. Owing to the integration of optics and microfluidics technologies, optofluidic technology enables highly precise flow manipulation and highly sensitive signal detection at the microscale, thus offering the promising potential for developing biodiagnostic applications. Research toward this direction is fast growing into an emerging area. In this paper, we give an overview of emerging optofluidic technologies for biodiagnostic applications with the focus on three common types of biomarkers: nucleic acid, protein, and cell. We conclude by discussing the challenges, opportunities, and future perspectives of this field.

Paths for improvements of smallholder dairies: Case-study on local food security in arid regions of China

The trend today leans towards urbanization and large farming enterprises. However, in 2019–2020, with the impact of the COVID-19 pandemic, the supply of commercial milk was disrupted, and the local smallholder dairy farmers played an important role in stabilizing nutritional security in rural, arid areas of China. The aim of this study was to describe and understand the operation of smallholder dairy farms and suggest what improvements are needed. We interviewed 45 smallholder dairy farmers from Gansu Province. A questionnaire was used to collect information on the dairy operation, including, number of cows, cow breeds, feed offered, yield and on management and open-ended discussions on the needs of the farmers to improve their dairies. Feed samples were collected at each farm to determine composition and milk samples were collected to analyze for composition and fatty acid content, and to compare the quality with commercial milk. Smallholder farmers generally fed dairy cows local, low-quality forages, mainly wheat straw and corn stover (CS/WS), and the milk yield was low, however, milk had a high content of beneficial unsaturated and polyunsaturated fatty acids. Milk from smallholder farms had lower concentrations of undesirable saturated fatty acids, higher concentrations of beneficial unsaturated and polyunsaturated fatty acids, and a lower atherogenic index than commercial milk. Proper sanitation measures and veterinary care were often lacking in these remote areas, leading to high somatic cell counts (SCC). A modified version of grounded theory was used to construct categories of what the farmers perceived was needed to improve their dairies. Four categories emerged in the following order: 1) equipment and management, 2) government support, 3) better cows, and 4) better feed. In a follow-up survey in 2020 of 18 farmers, conditions generally remained the same, including feed offered the animals, which would indicate that the milk composition remained the same. It was concluded that smallholder dairy farmers can provide nutritional security, especially for local residents in remote, rural, arid areas, but improvements in facilities, management, feed, cow breeds and sanitation are needed. Government subsidies should be implemented to help the smallholder dairy farmers. Results from this study provide information for local governments in their decision-making policies to stabilize smallholder dairies.

Single-cell epigenomic landscape of peripheral immune cells reveals establishment of trained immunity in individuals convalescing from COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection often causes severe complications and even death. However, asymptomatic infection has also been reported, highlighting the difference in immune responses among individuals. Here we performed single-cell chromatin accessibility and T cell-receptor analyses of peripheral blood mononuclear cells collected from individuals convalescing from COVID-19 and healthy donors. Chromatin remodelling was observed in both innate and adaptive immune cells in the individuals convalescing from COVID-19. Compared with healthy donors, recovered individuals contained abundant TBET-enriched CD16+ and IRF1-enriched CD14+ monocytes with sequential trained and activated epigenomic states. The B-cell lineage in recovered individuals exhibited an accelerated developmental programme from immature B cells to antibody-producing plasma cells. Finally, an integrated analysis of single-cell T cell-receptor clonality with the chromatin accessibility landscape revealed the expansion of putative SARS-CoV-2-specific CD8+ T cells with epigenomic profiles that promote the differentiation of effector or memory cells. Overall, our data suggest that immune cells of individuals convalescing from COVID-19 exhibit global remodelling of the chromatin accessibility landscape, indicative of the establishment of immunological memory.

A graphene oxide coated tapered microfiber acting as a super-sensor for rapid detection of SARS-CoV-2.

COVID-19 is a new strain of highly contagious coronavirus, and at present, more than 221.4 million people have been infected with this virus, and the death toll exceeds 2793398. Early and fast detection of COVID-19 from infected individuals is critical to limit its spreading. Here, we report an innovative approach to detect the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N) protein by combining DNA/RNA oligomers as aptamers and a graphene oxide (GO) coated optical microfiber as a sensor system. The DNA/RNA aptamers can effectively capture the SARS-CoV-2 N protein in vitro, with the GO coated optical microfiber aptasensor for real-time monitoring of the SARS-CoV-2 N protein. Due to the extremely high surface-to-volume ratio and excellent optical and biochemical properties of the GO surface layer, the fixing effect of the microfiber surface is significantly improved and the lowest limit of detection (LOD) is 6.25 × 10-19 M. Furthermore, in order to prove the feasibility of this sensing method in clinical applications, we use this sensor to detect the N protein mixed in fetal bovine serum (FBS) samples. The experimental results show that the biosensor can quickly and effectively detect the N protein (1 × 10-9 M) in a complex sample matrix within 3 minutes. These findings suggest that this approach can be utilized for quantitative monitoring of coronavirus particles due to its high sensitivity, which can help to quickly exclude patients who do not have the infection. Collectively, the optical microfiber sensor system could be expected to become an important platform for the diagnosis of coronavirus due to its simple detection scheme and easy miniaturization.

Elevated glucose level leads to rapid COVID-19 progression and high fatality.

OBJECTIVES: We aimed to identify high-risk factors for disease progression and fatality for coronavirus disease 2019 (COVID-19) patients. METHODS: We enrolled 2433 COVID-19 patients and used LASSO regression and multivariable cause-specific Cox proportional hazard models to identify the risk factors for disease progression and fatality. RESULTS: The median time for progression from mild-to-moderate, moderate-to-severe, severe-to-critical, and critical-to-death were 3.0 (interquartile range: 1.8-5.5), 3.0 (1.0-7.0), 3.0 (1.0-8.0), and 6.5 (4.0-16.3) days, respectively. Among 1,758 mild or moderate patients at admission, 474 (27.0%) progressed to a severe or critical stage. Age above 60 years, elevated levels of blood glucose, respiratory rate, fever, chest tightness, c-reaction protein, lactate dehydrogenase, direct bilirubin, and low albumin and lymphocyte count were significant risk factors for progression. Of 675 severe or critical patients at admission, 41 (6.1%) died. Age above 74 years, elevated levels of blood glucose, fibrinogen and creatine kinase-MB, and low plateleta count were significant risk factors for fatality. Patients with elevated blood glucose level were 58% more likely to progress and 3.22 times more likely to die of COVID-19. CONCLUSIONS: Older age, elevated glucose level, and clinical indicators related to systemic inflammatory responses and multiple organ failures, predict both the disease progression and the fatality of COVID-19 patients.

Increased circulating level of interleukin-6 and CD8+ T cell exhaustion are associated with progression of COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is pandemic. It is critical to identify COVID-19 patients who are most likely to develop a severe disease. This study was designed to determine the clinical and epidemiological features of COVID-19 patients associated with the development of pneumonia and factors associated with disease progression. METHODS: Seventy consecutive patients with etiologically confirmed COVID-19 admitted to PLA General Hospital in Beijing, China from December 27, 2019 to March 12, 2020 were enrolled in this study and followed-up to March 16, 2020. Differences in clinical and laboratory findings between COVID-19 patients with pneumonia and those without were determined by the χ2 test or the Fisher exact test (categorical variables) and independent group t test or Mann-Whitney U test (continuous variables). The Cox proportional hazard model and Generalized Estimating Equations were applied to evaluate factors that predicted the progression of COVID-19. RESULTS: The mean incubation was 8.67 (95% confidence interval, 6.78-10.56) days. Mean duration from the first test severe acute respiratory syndrome coronavirus 2-positive to conversion was 11.38 (9.86-12.90) days. Compared to pneumonia-free patients, pneumonia patients were 16.5 years older and had higher frequencies of having hypertension, fever, and cough and higher circulating levels of neutrophil proportion, interleukin-6, low count (< 190/µl) of CD8+ T cells, and neutrophil/lymphocyte ratio. Thirteen patients deteriorated during hospitalization. Cox regression analysis indicated that older age and higher serum levels of interleukin-6, C-reactive protein, procalcitonin, and lactate at admission significantly predicted the progression of COVID-19. During hospitalization, circulating counts of T lymphocytes, CD4+ T cells, and CD8+ T cells were lower, whereas neutrophil proportion, neutrophil/lymphocyte ratio, and the circulating levels of interleukin-6, C-reactive protein, and procalcitonin were higher, in pneumonia patients than in pneumonia-free patients. CD8+ lymphocyte count in pneumonia patients did not recover when discharged. CONCLUSIONS: Older age and higher levels of C-reactive protein, procalcitionin, interleukin-6, and lactate might predict COVID-19 progression. T lymphocyte, especially CD8+ cell-mediated immunity is critical in recovery of COVID-19. This study may help in predicting disease progression and designing immunotherapy for COVID-19.

Human umbilical cord-derived mesenchymal stem cell therapy in patients with COVID-19: a phase 1 clinical trial.

No effective drug treatments are available for coronavirus disease 2019 (COVID-19). Host-directed therapies targeting the underlying aberrant immune responses leading to pulmonary tissue damage, death, or long-term functional disability in survivors require clinical evaluation. We performed a parallel assigned controlled, non-randomized, phase 1 clinical trial to evaluate the safety of human umbilical cord-derived mesenchymal stem cells (UC-MSCs) infusions in the treatment of patients with moderate and severe COVID-19 pulmonary disease. The study enrolled 18 hospitalized patients with COVID-19 (n = 9 for each group). The treatment group received three cycles of intravenous infusion of UC-MSCs (3 × 107 cells per infusion) on days 0, 3, and 6. Both groups received standard COVID-treatment regimens. Adverse events, duration of clinical symptoms, laboratory parameters, length of hospitalization, serial chest computed tomography (CT) images, the PaO2/FiO2 ratio, dynamics of cytokines, and IgG and IgM anti-SARS-CoV-2 antibodies were analyzed. No serious UC-MSCs infusion-associated adverse events were observed. Two patients receiving UC-MSCs developed transient facial flushing and fever, and one patient developed transient hypoxia at 12 h post UC-MSCs transfusion. Mechanical ventilation was required in one patient in the treatment group compared with four in the control group. All patients recovered and were discharged. Our data show that intravenous UC-MSCs infusion in patients with moderate and severe COVID-19 is safe and well tolerated. Phase 2/3 randomized, controlled, double-blinded trials with long-term follow-up are needed to evaluate the therapeutic use of UC-MSCs to reduce deaths and improve long-term treatment outcomes in patients with serious COVID-19.

Effect of COVID-19 on patients with compensated chronic liver diseases.

BACKGROUND AND AIM: Cytokine storm has been reported in patients with coronavirus disease 2019 (COVID-19) due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. We examine the incidence of acute on chronic liver failure (ACLF) in COVID-19 patients with pre-existing compensated chronic liver disease (CLD). METHODS: From 20 Jan 2020 to 7 Feb 2020, we studied 140 consecutive COVID-19 patients admitted to either Fuyang Second People's Hospital (FYSPH), Anhui or the Fifth Medical Center of Chinese PLA General Hospital (PLAGH) in Beijing, China. Pre-existing CLD includes those with liver cirrhosis assessed by APRI/FIB-4 score and /or ultrasound; NAFLD as identified by either ultrasound or hepatic steatosis index with significant liver fibrosis and chronic hepatitis B (CHB) or hepatitis C (CHC) infection. The diagnosis, grading of severity and clinical management of COVID-19 patients complied to the guideline and clinical protocol issued by the China National Health Commission. All patients had liver function test at least twice weekly till discharge with full recovery or death. RESULTS: In total, 3 had liver cirrhosis, 6 patients had CHB, 13 had NAFLD with significant liver fibrosis (one also had CHB). On admission, none had liver decompensation. COVID-19 disease progression was significantly less frequent in non-CLD patients (10/118 8.5%) than CLD patients (13/22 59.1%, p < 0.001). One patient with CLD had acute-on-chronic liver failure (ACLF). CONCLUSION: Disease progression is significantly higher in those COVID-19 patients with CLD as compared to those with no CLD. ACLF can also occur in patient with pre-existing compensated CLD who had severe COVID-19.