Biochemical Characterization of a Flavone Synthase I from Daucus carota and its Application for Bioconversion of Flavanones to Flavones.

In this study, we studied the biochemical characterization of flavone synthase I from Daucus carota (DcFNS I) and applied it with flavonoid 6-hydroxylase from Scutellaria baicalensis (SbCYP) to convert flavanones to flavones. The recombinant DcFNS I was expressed in the form of the glutathione-S-transferase fusion protein. Rather than taxifolin, naringenin, pinocembrin, and eriodictyol were accepted as substrates. The optimal temperature and pH for reaction in vitro were 35 °C and 7.5, respectively, and 2-oxoglutarate was essential in the assay system. Co2+, Cu2+, Mn2+, Ni2+, and Zn2+ were not substitutes for Fe2+. EDTA and pyruvic acid inhibited the activity, except for Fe3+. Kinetic analysis revealed that the Vmax and kcat values of the recombinant DcFNS I against naringenin were 0.183 nmol mg-1 s-1 and 0.0121 s-1, and 0.175 nmol mg-1 s-1 and 0.0116 s-1 against pinocembrin. However, the recombinant DcFNS I had a higher affinity for naringenin than pinocembrin, with kM values for each of 0.076 mM and 0.174 mM respectively. Thus, it catalyzed naringenin more efficiently than pinocembrin. Subsequently, using an Escherichia coli and Saccharomyces cerevisiae co-culture system, we successfully converted naringenin and pinocembrin to scutellarein and baicalein respectively. In a synthetic complete medium, the titers of scutellarein and baicalein reached 5.63 mg/L and 0.78 mg/L from 200 mg/L precursors.

The Impact of Tax Reduction and Fee Reduction Based on Big Data Algorithm on the High-Quality Development of the Real Economy under the Action of Coupling Effect or Substitution Effect.

The basic idea of the mass of medical growth is to adhere to local market price thinking with a Chinese touch and follow the development policy of "quality first, efficiency first." It insists on properly handling a series of important relationships betwixt socialism and market economy, the first to drive the rich later, the government and the market, equality and efficiency, short-term growth and long-term development, China and the international economy, ecology and growth of the region. Under the guidance of the qualitative thinking theory, it combines the strategic goals of China's economic qualitative development and actively draws on the research results of other countries. It uses big data algorithms to focus on the impact of qualitative development on tax and income reduction in the real economy. It conducts research experiments on the impact of tax reduction and fee reduction based on big data algorithms on the top-notch growth of the real economy. Its experimental data show that: in 2018, the share of primary, tertiary, and primary sector in China's dimensional economy top-notch growth coordination index was 7.2%, 40.7%, and 52.2%, respectively. Its contribution rate to economic growth was 4.2%, 36.1%, and 59.7%, respectively. From these data, it can be concluded that the top-notch growth of the real economy is getting better and better under the influence of tax reduction and fee reduction by big data algorithms.

COVID-19 metabolism: Mechanisms and therapeutic targets.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) dysregulates antiviral signaling, immune response, and cell metabolism in human body. Viral genome and proteins hijack host metabolic network to support viral biogenesis and propagation. However, the regulatory mechanism of SARS-CoV-2-induced metabolic dysfunction has not been elucidated until recently. Multiomic studies of coronavirus disease 2019 (COVID-19) revealed an intensive interaction between host metabolic regulators and viral proteins. SARS-CoV-2 deregulated cellular metabolism in blood, intestine, liver, pancreas, fat, and immune cells. Host metabolism supported almost every stage of viral lifecycle. Strikingly, viral proteins were found to interact with metabolic enzymes in different cellular compartments. Biochemical and genetic assays also identified key regulatory nodes and metabolic dependencies of viral replication. Of note, cholesterol metabolism, lipid metabolism, and glucose metabolism are broadly involved in viral lifecycle. Here, we summarized the current understanding of the hallmarks of COVID-19 metabolism. SARS-CoV-2 infection remodels host cell metabolism, which in turn modulates viral biogenesis and replication. Remodeling of host metabolism creates metabolic vulnerability of SARS-CoV-2 replication, which could be explored to uncover new therapeutic targets. The efficacy of metabolic inhibitors against COVID-19 is under investigation in several clinical trials. Ultimately, the knowledge of SARS-CoV-2-induced metabolic reprogramming would accelerate drug repurposing or screening to combat the COVID-19 pandemic.

Roles and Challenges for Village Doctors in COVID-19 Pandemic Prevention and Control in Rural Beijing, China: A Qualitative Study

Objectives Rural areas in China are more vulnerable to COVID-19 pandemic than urban areas, due to their far fewer health care resources. Village doctors, as rural grassroots health workers in China, have been actively engaged in the pandemic prevention and control. This study aims to describe the roles of village doctors in rural China, and the challenges they have faced during the prevention and control of the COVID-19 pandemic. Setting This study was conducted in three towns in Huairou District, Beijing, China. Design We carried out semi-structured interviews with 75 key informants. All the interviews were audio-recorded and transcribed verbatim. We employed thematic analysis to define themes and sub-themes from the qualitative data. Results We reported four themes. First, the village doctor guided the village committee to carry out decontamination, monitored home-isolated residents, and disseminated knowledge on prevention of the COVID-19 pandemic during the rural pandemic prevention and control. Second, they took pandemic prevention measures in village clinics, distributed pandemic prevention materials, and undertook pre-screening triage. Third, village doctors provided basic medical care, including treatment of common diseases as well as the purchase and delivery of medicines to villagers. Fourth, village doctors faced difficulties and challenges, such as inadequate medical skills, aging staff structure, and lack of pandemic prevention materials. Conclusions Despite many difficulties and challenges, village doctors have actively participated in rural pandemic prevention and control, and made outstanding contributions to curbing spread of COVID-19 pandemic in rural areas. Village doctors provide basic health care while participating in various non-medical tasks.

Analysis of the Protective Efficacy of Approved COVID-19 Vaccines Against Various Mutants.

The outbreak of COVID-19 (caused by SARS-CoV-2) has posed a significant threat to global public health security because of its high pathogenicity and infectivity. To date, the pathogenic mechanism of this novel coronavirus (SARS-CoV-2) is still unclear, and there is no effective treatment. As one of the most effective strategies to prevent viral infection, vaccines have become a research hotspot. Based on the current understanding of SARS-CoV-2, the research and development of its vaccines cover almost all forms of current vaccine research, including inactivated vaccines, recombinant protein vaccines, viral vector vaccines, and nucleic acid vaccines. Moreover, with the spread of the new mutant virus, it is necessary to evaluate the protection rate of previous administered vaccines. This article reviews the candidate targets, vaccine types, research and development status, progress of SARS-CoV-2 vaccines, and the effectiveness of neutralizing antibodies against SARS-CoV-2 mutants (B.1.1.7, B.1.351, P.1, B.1.617.2, and B.1.1.529) induced by these vaccines, to provide a reference for follow-up research and prevention.

Progress on SARS-CoV-2 3CLpro Inhibitors: Inspiration from SARS-CoV 3CLpro Peptidomimetics and Small-Molecule Anti-Inflammatory Compounds.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) currently poses a threat to human health. 3C-like proteinase (3CLpro) plays an important role in the viral life cycle. Hence, it is considered an attractive antiviral target protein. Whole-genome sequencing showed that the sequence homology between SARS-CoV-2 3CLpro and SARS-CoV 3CLpro is 96.08%, with high similarity in the substrate-binding region. Thus, assessing peptidomimetic inhibitors of SARS-CoV 3CLpro could accelerate the development of peptidomimetic inhibitors for SARS-CoV-2 3CLpro. Accordingly, we herein discuss progress on SARS-CoV-2 3CLpro peptidomimetic inhibitors. Inflammation plays a major role in the pathophysiological process of COVID-19. Small-molecule compounds targeting 3CLpro with both antiviral and anti-inflammatory effects are also briefly discussed in this paper.

Alterations of Urinary Microbial Metabolites and Immune Indexes Linked With COVID-19 Infection and Prognosis

Coronavirus disease 2019 (COVID-19) has evolved into an established global pandemic. Metabolomic studies in COVID-19 patients is worth exploring for further available screening methods. In our study, we recruited a study cohort of 350 subjects comprising 248 COVID-19 patients (161 non-severe cases, 60 asymptomatic cases, and 27 severe cases) and 102 healthy controls (HCs), and herein present data with respect to their demographic features, urinary metabolome, immunological indices, and follow-up health status. We found that COVID-19 resulted in alterations of 39 urinary, mainly microbial, metabolites. Using random forest analysis, a simplified marker panel including three microbial metabolites (oxoglutaric acid, indoxyl, and phenylacetamide) was constructed (AUC=0.963, 95% CI, 0.930-0.983), which exhibited higher diagnostic performance than immune feature-based panels between COVID-19 and HC groups (P<0.0001). Meanwhile, we observed that urine metabolic markers enabled discriminating asymptomatic patients (ASY) from HCs (AUC = 0.981, 95% CI, 0.946-0.996), and predicting the incidence of high-risk sequalae in COVID-19 individuals (AUC=0.931, 95% CI, 0.877-0.966). Co-expression network analysis showed that 13 urinary microbial metabolites (e.g., oxoglutaric acid) were significantly correlated with alterations of CD4+, CD3+, and CD8+ T-cells, as well as IFN-γ, IL-2 and IL-4 levels, suggesting close interactions between microbial metabolites and host immune dysregulation in COVID-19. Taken together, our findings indicate that urinary metabolites may have promising potential for screening of COVID-19 in different application scenarios, and provide a new entry point to understand the microbial metabolites and related immune dysfunction in COVID-19.

Nurses' experiences of providing care to patients with COVID-19 in the ICU in Wuhan: a descriptive phenomenological research.

OBJECTIVES: This phenomenological study aimed to examine intensive care unit (ICU) nurses' experiences of caring for patients with COVID-19, and understand better their everyday experiences of patient' management in the ICU. DESIGN: A descriptive phenomenological research design was used. Individual interviews were conducted. The data were transcribed verbatim and analysed using Colaizzi's seven-step framework. SETTING: An ICU with 16 beds in a tertiary hospital in Wuhan, China. PARTICIPANTS: Nurses who had more than 1 year of experience and had provided care to patients with COVID-19 in ICU for more than 1 week were identified as participants. A total of 13 nurses were interviewed. RESULTS: An analysis of these significant statements yielded four distinct stages of feelings, thereby revealing the essence of this phenomenon. Worry about being infected and infecting family members was present across in all four stages. The themes associated with the four stages were as follows: initial contradictory feelings, quick adaption to the 'new working environment' in the first 1-2 weeks in the ICU, desperation after adaption, holding on and survive. CONCLUSIONS: The nurses reported distinct experiences of providing care to patients with COVID-19 in ICUs. Interventions, such as providing information about the disease, simulation training, emotional support and follow-up care, are needed to help nurses manage patients with COVID-19 and maintain nurses' health.

The Potential Role of Extracellular Vesicles in COVID-19 Treatment: Opportunity and Challenge.

SARS-CoV-2 infection has become an urgent public health concern worldwide, severely affecting our society and economy due to the long incubation time and high prevalence. People spare no effort on the rapid development of vaccine and treatment all over the world. Amongst the numerous ways of tackling this pandemic, some approaches using extracellular vesicles (EVs) are emerging. In this review, we summarize current prevalence and pathogenesis of COVID-19, involving the combination of SARS-CoV-2 and virus receptor ACE2, endothelial dysfunction and micro thrombosis, together with cytokine storm. We also discuss the ongoing EVs-based strategies for the treatment of COVID-19, including mesenchymal stem cell (MSC)-EVs, drug-EVs, vaccine-EVs, platelet-EVs, and others. This manuscript provides the foundation for the development of targeted drugs and vaccines for SARS-CoV-2 infections.

Discovery of sandwich type COVID-19 nucleocapsid protein DNA aptamers.

Here, we report for the first time DNA aptamers targeted toward the COVID-19 nucleocapsid protein (Np). Np is one of the most abundant structural proteins and it serves as a diagnostic marker for the accurate and sensitive detection of COVID-19. After five rounds of selection, we obtained four DNA sequences with an affinity below 5 nM. The best one displayed a superb binding performance toward Np with a Kd value of 0.49 nM. Interestingly, we found that the four pairs of aptamers could bind to Np successively, suggesting a sandwich-type interaction. Using these sandwiched aptamers in ELISA and colloidal gold immunochromatographic strips, we were able to detect Np at the tens of pM level. The results demonstrate that aptamers are powerful molecular tools for virus detection, diagnosis, and antiviral therapy.