Expression of water-soluble nucleocapsid protein of SARS-CoV-2 and analysis of its immunogenicity

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to be a major public health concern. Nucleocapsid (N) protein is the most abundant structural protein on SARS-CoV-2 virions and induces the production of antibodies at the early stage of infection. Large-scale preparation of N protein is essential for the development of immunoassays to detect antibodies to SARS-CoV-2 and the control of virus transmission. In this study, expression of water-soluble N protein was achieved through inducing protein expression at 25°C with 0.5 mM IPTG for 12 h. Western blot and ELISA showed that recombinant N protein could be recognized by sera collected from subjects immunized with Sinovac inactivated SARS-CoV-2 vaccine. Four monoclonal antibodies namely 2B1B1, 4D3A3, 5G1F8, and 7C6F5 were produced using hybridoma technology. Titers of all four monoclonal antibodies in ELISA reached more than 1.28×10 6.0. Moreover, all monoclonal antibodies could react specifically with N protein expressed by transfection of pcDNA3.1-N into BHK-21 cells in IPMA and IFA. These results indicated that water-soluble N protein retained high immunogenicity and possessed the same epitopes as that of native N protein on virions. In addition, the preparation of water-soluble N protein and its monoclonal antibodies laid the basis for the development of immunoassays for COVID-19 detection.

Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations

The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9}  GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.

[Clinical features, risk factors and prognosis of idiopathic dilated cardiomyopathy complicated by ischemic stroke]

Objective: To analyze the clinical features, risk factors and prognosis of idiopathic dilated cardiomyopathy (DCM) complicated with ischemic stroke (IS) (DCM-IS). Methods: The clinical data of patients with idiopathic DCM (n=613) in Beijing Anzhen Hospital, Liangxiang Hospital and Fuxing Hospital from January 2016 to December 2020 were retrospectively collected, and among them, 123 cases were DCM-IS. Clinical features of patients with DCM-IS were summarized and multivariate logistic regression model was utilized to analyze the independent risk factors of DCM-IS. Furthermore, 1-year follow-up was conducted and Kaplan-Meier curve was adopted to analyze the prognosis of DCM, using all-cause death and heart transplantation as adverse outcomes. Results: Among the 70 patients with DCM-IS, 6 patients (8.6%, 6/70) were in accordance with the subtype of large artery atherosclerosis, and 47 patients (67.1%, 47/70) were in line with the subtype of cardiogenic embolism, and small artery occlusion subtype (ie, lacunar infarction) were detected in 17 cases (24.3%, 17/70). Hypertension [odds ratio (OR)=1.617, 95% confidence interval (CI): 1.049-2.491, P=0.029], hyperlipidemia (OR=1.918, 95%CI: 1.198-3.073, P=0.007), atrial fibrillation (AF) (OR=1.617, 95%CI: 1.016-2.572, P=0.043), lower estimated glomerular filtration rate (eGFR) (OR=0.986, 95%CI: 0.977-0.996, P=0.005) and a higher incidence of intracardiac thrombus (OR=6.127, 95%CI: 3.174-11.827, P<0.001) were risk factors for DCM-IS. The overall 1-year survival rate was lower in DCM-IS patients (70.7%) than DCM patients without stroke (83.6%, P=0.004), and the main causes of death included obstinate heart failure (3 cases of DCM-IS, and 5 cases of non-DCM-IS) and malignant arrhythmia (DCM-IS) (22 cases of DCM-IS, and 18 cases of non-DCM-IS). Conclusions: Among IS patients with idiopathic DCM, cardioembolism is the most common, followed by lacunar infarction, and the large-artery atherosclerotic subtype is the least common.Hypertension, hyperlipidemia, AF, lower eGFR value and higher incidence of intracardiac thrombus are risk factors for DCM-IS. DCM patients complicated with IS have poor short-term prognosis, and obstinate heart failure and malignant arrhythmia are their main causes of death.

[Evaluation of safety and clinical efficacy of bilateral percutaneous kyphoplasty in treatment of osteoporotic thoraco-lumbar burst fractures]

Objective: To evaluate the safety and clinical efficacy of bilateral percutaneous kyphoplasty (PKP) in the treatment of osteoporotic vertebral burst fractures. Methods: It was a prospective study, 28 patients with osteoporotic thoraco-lumbar burst fractures who were treated in Beijing Chao-Yang Hospital from January 2021 to July 2021 were included, including 10 males and 18 females, with a median age of 73.6 years (range: 56.0-87.0 years). The X-ray radiographs, bone mineral density (BMD), CT three-dimensional reconstruction scan and MRI were taken and measured before operation to observe the fracture location and the posterior wall of the vertebral body, and further to determine the diagnosis. The X-ray radiographs and CT three-dimensional reconstruction scans were taken on the first day after operation and the last follow-up to observe whether there were bone cement leakage or not. The changes of kyphosis angle (KA), the height of anterior wall (HAW) and the height of posterior wall (HPW) before the operation, on the 1st day post operation and at the last follow-up were recorded. The visual analogue scale (VAS) of back pain and Oswestry dysfunction index (ODI) before the operation, 1 day post operation and at the last follow-up were used to evaluate the clinical effect of the operation. Results: All the patients were followed up for (12.2±6.0) months. The HAW on the 1st day post operation [(22.5±2.0) mm] was significantly increased as compared with that before the operation [(21.2±2.4) mm] (P<0.05). The HAW at the last follow-up [(18.9±1.6) mm] decreased signficantly as compared with that on the 1st day post opertion [(22.5±2.0) mm] (P<0.05). The HPW was also significantly corrected after surgery (P<0.05). At the end of the follow-up, the HPW [(27.2±1.3) mm] was comparable with that on the 1st day after surgery [(27.5±1.6) mm] (P>0.05). The KA on the 1st day after the operation (14.2°±1.5°) decreased significantly when compared with that before the operation (18.8°±1.3°) (P<0.05), but it was increased to 17.6°±1.4° at the last follow-up and was higher than that on the 1st day after the operation (P<0.05). There were bone cement leakage in 5 cases and adjacent vertebral fracture in 1 case. The VAS and ODI scores were all significantly lower on the 1st day and at last follow-up than that before the operation (all P<0.05). Conclusions: Bilateral PKP is effective, safe and reliable in the treatment of osteoporotic vertebral burst fracture. Careful evaluation of preoperative imaging data, accurate puncture and timing of bone cement injection are the key factors to ensure the success of the operation.

Human adipose-derived stem cell-loaded small intestinal submucosa as a bioactive wound dressing for the treatment of diabetic wounds in rats

Chronic nonhealing wounds are one of the most common and serious complications of diabetes, which can lead to disability of patients. Adipose-derived stem cells (ADSCs) have emerged as a promising tool for skin wound healing, but the therapeutic potential depends considerably on the cell delivery system. Small intestinal submucosa (SIS) is an extracellular matrix-based membranous scaffold with outstanding repair potential for skin wounds. In this study, we first fabricated a bioactive wound dressing, termed the SIS+ADSCs composite, by using human ADSCs as the seed cell and porcine SIS as the cell delivery vehicle. Then, we systematically investigated, for the first time, the healing potential of this wound dressing in a rat model of type 2 diabetes. In vitro studies revealed that SIS provided a favorable microenvironment for ADSCs and significantly promoted the expression of growth factors critical for chronic wound healing. After implantation in the full-thickness skin wounds of diabetic rats, the SIS+ADSCs composite showed a higher wound healing rate and wound healing quality than those in the PBS, ADSCs, and SIS groups. Along with the ability to modulate the polarization of macrophages in vivo, the SIS+ADSCs composite was potent at promoting wound angiogenesis, reepithelialization, and skin appendage regeneration. Taken together, these results indicate that the SIS+ADSCs composite has good therapeutic potential and high translational value for diabetic wound treatment.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

Peta-electron volt gamma-ray emission from the Crab Nebula

The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar's rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10^-4 to 1.1 peta-electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta-electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron's size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta-electron volt electrons, 2.5 × 10³⁶ ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta-electron volt protons to the production of the highest-energy gamma rays.

Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A

We report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (207.8 kyr) pulsar PSR J0622+3749 with the Large High-Altitude Air Shower Observatory (LHAASO). The source is detected with a significance of 8.2σ for E>25  TeV assuming a Gaussian template. The best-fit location is (right ascension, declination) =(95.47°±0.11°,37.92°±0.09°), and the extension is 0.40°±0.07°. The energy spectrum can be described by a power-law spectrum with an index of -2.92±0.17_{stat}±0.02_{sys}. No clear extended multiwavelength counterpart of the LHAASO source has been found from the radio to sub-TeV bands. The LHAASO observations are consistent with the scenario that VHE electrons escaped from the pulsar, diffused in the interstellar medium, and scattered the interstellar radiation field. If interpreted as the pulsar halo scenario, the diffusion coefficient, inferred for electrons with median energies of ∼160  TeV, is consistent with those obtained from the extended halos around Geminga and Monogem and much smaller than that derived from cosmic ray secondaries. The LHAASO discovery of this source thus likely enriches the class of so-called pulsar halos and confirms that high-energy particles generally diffuse very slowly in the disturbed medium around pulsars.

Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources

The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10¹⁵ electronvolts) indicates the existence of the so-called PeVatrons-cosmic-ray factories that accelerate particles to PeV energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays¹. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref. ²). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane^3-6, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators.

[Using structured decision-making to identify the appropriate type of entity for the centers for disease control and prevention of China]

Objective: To develop evidence-based appropriate type of entity for the Centers for Disease Control and Prevention in order to improve the performance of disease control and prevention system in China. Methods: This study firstly proposed the core functions and essential public health programs for the Centers for Disease Control and Prevention. Using Structured Decision-Making, this study presented three alternative options for type of entity to make essential public health programs succeed, and reviewed the pros and cons of alternative options based on 15 evaluation indicators. Questionnaires were distributed to 47 stakeholders between April 10 and April 20 of 2020. Finally, an appropriate type of entity for the Centers for Disease Control and Prevention was identified by using both qualitative and quantitative methods. Results: A total of 47 stakeholders ranked alternative options. Aggregated scores of each alternative option was computed after weighting each indicators. The results shows that Option 1(professional technical civil service organization)has the highest score (58.22). Conclusion: Professional technical civil service organization is appropriate type of entity for Centers for Disease Control and Prevention.

Biotransformation of insecticide flonicamid by Aminobacter sp. CGMCC 1.17253 via nitrile hydratase catalysed hydration pathway

AIMS

This study evaluates flonicamid biotransformation ability of Aminobacter sp. CGMCC 1.17253 and the enzyme catalytic mechanism involved.

METHODS AND RESULTS

Flonicamid transformed by resting cells of Aminobacter sp. CGMCC 1.17253 was carried out. Aminobacter sp. CGMCC 1.17253 converts flonicamid into N-(4-trifluoromethylnicotinoyl) glycinamide (TFNG-AM). Aminobacter sp. CGMCC 1.17253 transforms 31·1% of the flonicamid in a 200 mg l^-1 conversion solution in 96 h. Aminobacter sp. CGMCC 1.17253 was inoculated in soil, and 72·1% of flonicamid with a concentration of 0·21 μmol g^-1 was transformed in 9 days. The recombinant Escherichia coli expressing Aminobacter sp. CGMCC 1.17253 nitrile hydratase (NHase) and purified NHase were tested for the flonicamid transformation ability, both of them acquired the ability to transform flonicamid into TFNG-AM.

CONCLUSIONS

Aminobacter sp. CGMCC 1.17253 transforms flonicamid into TFNG-AM via hydration pathway mediated by cobalt-containing NHase.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report that bacteria of genus Aminobacter has flonicamid-transforming ability. This study enhances our understanding of flonicamid-degrading mechanism. Aminobacter sp. CGMCC 1.17253 has the potential for bioremediation of flonicamid pollution.

Placenta- versus bone-marrow-derived mesenchymal cells for the repair of segmental bone defects in a rabbit model

Tissue-engineered bones (TEBs) constructed with bone-marrow-derived mesenchymal stem cells (BMSCs) seeded on biomaterial scaffolds have achieved good results for bone defect repair in both animal experiments and clinical trials. This has been limited, however, by the source and quantity of BMSCs. We here explored TEBs constructed by placenta-derived mesenchymal stem cells (PMSCs) and compared their effect for the repair of critical-sized segmental osteoperiosteal defects with TEBs constructed with BMSCs. PMSCs were isolated from rabbit placenta by gradient centrifugation and in vitro monolayer culturing, and BMSCs were isolated from the hindlimb bone marrow of newborn rabbit. Primary cultured PMSCs and BMSCs were uniformly in a spindle shape. Immunocytochemistry indicated that both types of cells are positive for CD44 and CD105, and negative for CD34 and CD40L, confirming that they are mesenchymal stem cells. BrdU-labeled PMSCs and BMSCs were respectively co-cultured with bio-derived bone materials to construct TEBs in vitro. Critical-sized segmental osteoperiosteal defects of radii were created in 24 rabbits by surgery. The defects were repaired with TEBs constructed with PMSCs and BMSCs. The results showed that TEBs constructed by both PMSCs and BMSCs could repair the osteoperiosteal defects in a 'multipoint' manner. Measurement of radiography, histology, immunohistochemistry, alkaline phosphatase activity, osteocalcin assaying and biomechanical properties have found no significant difference between the two groups at 2, 4, 8 and 12 weeks after the transplantation (P > 0.05). Taken together, our results indicate that PMSCs have similar biological characteristics and osteogenic capacity to BMSCs and can be used as a new source of seeding cells for TEBs.

Biotype status and distribution of Bemisia tabaci (Hemiptera: Aleyrodidae) in Shandong province of China based on mitochondrial DNA markers

Bemisia tabaci has caused significant crop losses in China during the last decade. Recent research has shown that two potentially invasive variants, biotypes B and Q, have been found in several regions of China. Our objective was to determine the biotype status and the distribution of B. tabaci in Shandong province, an important agricultural region of China. Based on mitochondrial DNA markers, both biotypes B and Q were detected, with B being the predominant biotype. The results indicate that the more recently introduced biotype Q has not only been located in China but also has established and spread in some regions.