A comparative study on the three calculation methods for reproduction numbers of COVID-19

ObjectiveThis study uses four COVID-19 outbreaks as examples to calculate and compare merits and demerits, as well as applicational scenarios, of three methods for calculating reproduction numbers.MethodThe epidemiological characteristics of the COVID-19 outbreaks are described. Through the definition method, the next-generation matrix-based method, and the epidemic curve and serial interval (SI)-based method, corresponding reproduction numbers were obtained and compared.ResultsReproduction numbers (Reff), obtained by the definition method of the four regions, are 1.20, 1.14, 1.66, and 1.12. Through the next generation matrix method, in region H Reff = 4.30, 0.44; region P Reff = 6.5, 1.39, 0; region X Reff = 6.82, 1.39, 0; and region Z Reff = 2.99, 0.65. Time-varying reproduction numbers (Rt), which are attained by SI of onset dates, are decreasing with time. Region H reached its highest Rt = 2.8 on July 29 and decreased to Rt < 1 after August 4; region P reached its highest Rt = 5.8 on September 9 and dropped to Rt < 1 by September 14; region X had a fluctuation in the Rt and Rt < 1 after September 22; Rt in region Z reached a maximum of 1.8 on September 15 and decreased continuously to Rt < 1 on September 19.ConclusionThe reproduction number obtained by the definition method is optimal in the early stage of epidemics with a small number of cases that have clear transmission chains to predict the trend of epidemics accurately. The effective reproduction number Reff, calculated by the next generation matrix, could assess the scale of the epidemic and be used to evaluate the effectiveness of prevention and control measures used in epidemics with a large number of cases. Time-varying reproduction number Rt, obtained via epidemic curve and SI, can give a clear picture of the change in transmissibility over time, but the conditions of use are more rigorous, requiring a greater sample size and clear transmission chains to perform the calculation. The rational use of the three methods for reproduction numbers plays a role in the further study of the transmissibility of COVID-19

Modes of Antiviral Action of Chemical Portions and Constituents from Woad Root Extract against Influenza Virus A FM1

Woad root has been used for the prevention of influenza for hundreds of years in many Asian countries. In this study, the antiviral modes of clemastanin B (CB), epigoitrin, phenylpropanoid portion (PEP), and the mixture of phenylpropanoids, alkaloids, and organic acid portions (PEP + ALK + OA) from wood root extract against influenza virus A FM1 were investigated. The results revealed that CB, epigoitrin, PEP, and PEP + ALK + OA exert their anti-influenza activity via inhibiting the virus multiplication, prophylaxis, and blocking the virus attachment. The primary mode of action of PEP and PEP + ALK + OA is the inhibition of virus replication. The inhibitory effect on virus attachment and multiplication is the main modes for epigoitrin. All the compounds or chemical portions from woad root extract tested in this study do not have direct virucidal activity. Our results provided the comprehensive analysis of the antiviral mechanism of wood root extract

KLF7-transfected Schwann cell graft transplantation promotes sciatic nerve regeneration

Our former study demonstrated that Krüppel-like Factor 7 (KLF7) is a transcription factor that stimulates axonal regeneration after peripheral nerve injury. Currently, we used a gene therapy approach to overexpress KLF7 in Schwann cells (SCs) and assessed whether KLF7-transfected SCs graft could promote sciatic nerve regeneration. SCs were transfected by adeno-associated virus 2 (AAV2)-KLF7 in vitro. Mice were allografted by an acellular nerve (ANA) with either an injection of DMEM (ANA group), SCs (ANA + SCs group) or AAV2-KLF7-transfected SCs (ANA + KLF7-SCs group) to assess repair of a sciatic nerve gap. The results indicate that KLF7 overexpression promoted the proliferation of both transfected SCs and native SCs. The neurite length of the dorsal root ganglia (DRG) explants was enhanced. Several beneficial effects were detected in the ANA + KLF7-SCs group including an increase in the compound action potential amplitude, sciatic function index score, enhanced expression of PKH26-labeling transplant SCs, peripheral myelin protein 0, neurofilaments, S-100, and myelinated regeneration nerve. Additionally, HRP-labeled motoneurons in the spinal cord, CTB-labeled sensory neurons in the DRG, motor endplate density and the weight ratios of target muscles were increased by the treatment while thermal hyperalgesia was diminished. Finally, expression of KLF7, NGF, GAP43, TrkA and TrkB were enhanced in the grafted SCs, which may indicate that several signal pathways may be involved in conferring the beneficial effects from KLF7 overexpression. We concluded that KLF7-overexpressing SCs promoted axonal regeneration of the peripheral nerve and enhanced myelination, which collectively proved KLF-SCs as a novel therapeutic strategy for injured nerves

Effect of Exchange-type Zero-bias Anomaly on Single Electron Tunnelling of Au Nanoparticles

Using cryogenic scanning tunnelling microscopy and scanning tunnelling spectroscopy we measured single electron tunnelling of isolated Au nanoparticles with 1.4 nm in radius. We observe that a gap {\Delta}V ~ 2e/C (C is the capacitance of the Au particle) around zero bias in the tunnelling conductance spectrum, followed by a series of discrete single electron tunnelling peaks with voltage widths of EC ~ e/C at both negative and positive bias. Experimental data are well explained by taking into account the effect of exchange interaction of electrons on the single electron tunnelling of Au nanoparticles. A tunnelling peak near zero-bias was suppressed by the exchange-type zero-bias anomaly, which results in the gap {\Delta}V ~ 2EC.Comment: 4pages, 3 figure

SIJUNZI DECOCTION DEMOLITION PARTIES INHIBIT PROLIFERATION AND INDUCE APOPTOSIS OF HUMAN GASTRIC CANCER BGC823 SIDE POPULATION

Background: Comprehensive treatment combining with Chinese medicine has become the main therapeutic regimen of gastric cancer. Previous evidence demonstrated SD can enhance the effect of chemotherapy in advanced cancer, especially in gastric cancer. In order to investigate the anticancer mechanism of SD in gastric cancer, we observed the effects of SD parties (Ginseng, Atractylodes, Poria, Licorice) on proliferation and apoptosis of SP of human gastric cancer BGC-823. Materials and Methods: 1. BGC-823 side population cells were sorted through flow cytometry. 2. To detect the changes of proliferation of SP and NSP before and after the intervention of serum containing SD parties using cck-8 method. 3. To detect the changes of cell cycle and apoptosis of SP and NSP before and after the intervention of serum containing SD parties through flow cytometry. 4. To detect the effects of serum containing SD parties on apoptosis-related proteins Bax and Bcl-2 of SP and NSP before and after the intervention by western-blot. Results: It was found that four demolition parties serum treatments inhibited cell proliferation in a time-dependent manner. Compared with the control group (normal saline treatment), there were increase in G1/G0 phase population of SP and NSP, and decrease in G2/M and S phase population (

Synthetic lethality by targeting the RUVBL1/2-TTT complex in mTORC1-hyperactive cancer cells

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.Despite considerable efforts, mTOR inhibitors have produced limited success in the clinic. To define the vulnerabilities of mTORC1-addicted cancer cells and to find previously unknown therapeutic targets, we investigated the mechanism of piperlongumine, a small molecule identified in a chemical library screen to specifically target cancer cells with a hyperactive mTORC1 phenotype. Sensitivity to piperlongumine was dependent on its ability to suppress RUVBL1/2-TTT, a complex involved in chromatin remodeling and DNA repair. Cancer cells with high mTORC1 activity are subjected to higher levels of DNA damage stress via c-Myc and displayed an increased dependency on RUVBL1/2 for survival and counteracting genotoxic stress. Examination of clinical cancer tissues also demonstrated that high mTORC1 activity was accompanied by high RUVBL2 expression. Our findings reveal a previously unknown role for RUVBL1/2 in cell survival, where it acts as a functional chaperone to mitigate stress levels induced in the mTORC1-Myc-DNA damage axis.NIH 1RO1CA142805National Research Foundation of Korea (NRF) grant (NRF-2017R1C1B1006072

Multifunctional ytterbium oxide buffer for perovskite solar cells

Perovskite solar cells (PSCs) comprise a solid perovskite absorber sandwiched between several layers of different charge-selective materials, ensuring unidirectional current flow and high voltage output of the devices. A ‘buffer material’ between the electron-selective layer and the metal electrode in p-type/intrinsic/n-type (p-i-n) PSCs (also known as inverted PSCs) enables electrons to flow from the electron-selective layer to the electrode. Furthermore, it acts as a barrier inhibiting the inter-diffusion of harmful species into or degradation products out of the perovskite absorber. Thus far, evaporable organic molecules and atomic-layer-deposited metal oxides have been successful, but each has specific imperfections. Here we report a chemically stable and multifunctional buffer material, ytterbium oxide (YbOx), for p-i-n PSCs by scalable thermal evaporation deposition. We used this YbOx buffer in the p-i-n PSCs with a narrow-bandgap perovskite absorber, yielding a certified power conversion efficiency of more than 25%. We also demonstrate the broad applicability of YbOx in enabling highly efficient PSCs from various types of perovskite absorber layer, delivering state-of-the-art efficiencies of 20.1% for the wide-bandgap perovskite absorber and 22.1% for the mid-bandgap perovskite absorber, respectively. Moreover, when subjected to ISOS-L-3 accelerated ageing, encapsulated devices with YbOx exhibit markedly enhanced device stability