The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in an unprecedented public health crisis. Because of the novelty ...of the virus, there are currently no SARS-CoV-2-specific treatments or vaccines available. Therefore, rapid development of effective vaccines against SARS-CoV-2 are urgently needed. Here, we developed a pilot-scale production of PiCoVacc, a purified inactivated SARS-CoV-2 virus vaccine candidate, which induced SARS-CoV-2-specific neutralizing antibodies in mice, rats, and nonhuman primates. These antibodies neutralized 10 representative SARS-CoV-2 strains, suggesting a possible broader neutralizing ability against other strains. Three immunizations using two different doses, 3 or 6 micrograms per dose, provided partial or complete protection in macaques against SARS-CoV-2 challenge, respectively, without observable antibody-dependent enhancement of infection. These data support the clinical development and testing of PiCoVacc for use in humans.
Cytochrome P450 enzymes play important roles in the biosynthesis of macrolide antibiotics by mediating a vast variety of regio- and stereoselective oxidative modifications, thus improving their ...chemical diversity, biological activities, and pharmaceutical properties. Tremendous efforts have been made on engineering the reactivity and selectivity of these useful biocatalysts. However, the 20 proteinogenic amino acids cannot always satisfy the requirement of site-directed/random mutagenesis and rational protein design of P450 enzymes. To address this issue, herein, we practice the semi-rational non-canonical amino acid mutagenesis for the pikromycin biosynthetic P450 enzyme PikC, which recognizes its native macrolide substrates with a 12- or 14-membered ring macrolactone linked to a deoxyamino sugar through a unique sugar-anchoring mechanism. Based on a semi-rationally designed substrate binding strategy, non-canonical amino acid mutagenesis at the His238 position enables the unnatural activities of several PikC mutants towards the macrolactone precursors without any sugar appendix. With the aglycone hydroxylating activities, the pikromycin biosynthetic pathway is rewired by the representative mutant PikC
carrying a p-acetylphenylalanine residue at the His238 position and a promiscuous glycosyltransferase. Moreover, structural analysis of substrate-free and three different enzyme-substrate complexes of PikC
provides significant mechanistic insights into the substrate binding and catalytic selectivity of this paradigm biosynthetic P450 enzyme.
In this work, to explore potential substitutions for the Co binder phase, ultrafine-grain WC-based cermets with various binder phases of Co, Ni and AlCoCrNiFeCu HEA were prepared using the SPS ...method. Based on SPS, WC-based cermets were fabricated at higher speed, showing fine carbide particles less than 410 μm. The microstructure, mechanical properties and wear properties were systematically evaluated. By comparison, the grain size of WC was the lowest for WC-10Co, while WC-10 HEA cermet held the coarsest WC particles. The hardness and fracture toughness of WC-10 HEA were the best among all three samples, with values of 93.2 HRA and 11.3 MP·m
. However, the bending strength of WC-10HEA was about 56.1% lower than that of WC-10Co, with a value of 1349.6 MPa. The reduction in bending strength is attributed to the lower density, formation of a newly Cr-Al rich phase and coarser WC grains. In dry sliding wear conditions, WC-10 HEA showed the lowest wear rate (0.98 × 10
mm
/(N·m)) and coefficient of friction (0.19), indicating the best wear resistance performance. This reveals that WC-based cermet with a HEA binder phase has superior wear performance due to the higher hardness and good self-lubricating effect of the wear products.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Diterpene synthase VenA is responsible for assembling venezuelaene A with a unique 5-5-6-7 tetracyclic skeleton from geranylgeranyl pyrophosphate. VenA also demonstrates substrate promiscuity by ...accepting geranyl pyrophosphate and farnesyl pyrophosphate as alternative substrates. Herein, we report the crystal structures of VenA in both apo form and holo form in complex with a trinuclear magnesium cluster and pyrophosphate group. Functional and structural investigations on the atypical
DSFVSD
motif of VenA, versus the canonical Asp-rich motif of DDXX(X)D/E, reveal that the absent second Asp of canonical motif is functionally replaced by Ser116 and Gln83, together with bioinformatics analysis identifying a hidden subclass of type I microbial terpene synthases. Further structural analysis, multiscale computational simulations, and structure-directed mutagenesis provide significant mechanistic insights into the substrate selectivity and catalytic promiscuity of VenA. Finally, VenA is semi-rationally engineered into a sesterterpene synthase to recognize the larger substrate geranylfarnesyl pyrophosphate.
In this article, we propose a carbon nanotube (CNT) field-effect transistor (CNFET)-based static random access memory (SRAM) design at the 5-nm technology node that is optimized based on the tradeoff ...between performance, stability, and power efficiency. In addition to size optimization, physical model parameters including CNT density, CNT diameter, and CNFET flat band voltage are evaluated and optimized for CNFET SRAM performance improvement. Optimized CNFET SRAM is compared with state-of-the-art 7-nm FinFET SRAM cell based on Arizona State University ASAP 7-nm FinFET predictive technology models (PTM) library. We find that the read, write EDPs, and static power of the proposed CNFET SRAM cell are improved by 67.6%, 71.5%, and 43.6%, respectively, compared with the FinFET SRAM cell, with slightly better stability. CNT interconnects both inside and in-between CNFET SRAM cells are considered to compose an all-carbon-based SRAM (ACS) array which will be discussed in the Part II of this article. A 7-nm FinFET SRAM cell with copper interconnects is implemented and used for comparison.
Outbreaks of the highly pathogenic avian influenza H5N1 and H7N9 viruses have spurred an unprecedented research effort to develop antivirals and vaccines against influenza. Standardized methods for ...vaccine evaluation are critical for facilitating vaccine development. Compared with hemagglutination inhibition assays, mounting evidence suggest that microneutralization tests (MNTs) is a better choice for the evaluation of candidate pandemic influenza vaccines because they measure neutralizing antibody activity in cell cultures and are more sensitive in detecting H5 and H7. Here, we report a MNT measuring neuraminidase activity as the read-out (NA-MNT) for quantitative analysis of neutralizing antibodies against avian influenza viruses. Compared to the conventional microneutralization assay (ELISA-MNT), the NA-MNT is faster with lower intra- and inter-assay variations, while no difference in geometric mean titers was found between these two assays for the evaluation of H5N1 and H7N9 vaccines. These results suggest that NA-MNT is a reliable and high throughput method which could facilitate the development of candidate pandemic influenza vaccine.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mutated continuously and newly emerging variants escape from antibody-mediated neutralization raised great ...concern. S protein is heavily glycosylated and the glycosylation sites are relatively conserved, thus glycans on S protein surface could be a target for the development of anti-SARS-CoV-2 strategies against variants. Here, we collected 12 plant-derived lectins with different carbohydrate specificity and evaluated their anti-SARS-CoV-2 activity against mutant strains and epidemic variants using a pseudovirus-based neutralization assay. The Lens culinaris-derived lentil lectin which specifically bind to oligomannose-type glycans and GlcNAc at the non-reducing end terminus showed most potent and broad antiviral activity against a panel of mutant strains and variants, including the artificial mutants at N-/O-linked glycosylation site, natural existed amino acid mutants, as well as the epidemic variants B.1.1.7, B.1.351, and P.1. Lentil lectin also showed antiviral activity against SARS-CoV and MERS-CoV. We found lentil lectin could block the binding of ACE2 to S trimer and inhibit SARS-CoV-2 at the early steps of infection. Using structural information and determined N-glycan profile of S trimer, taking together with the carbohydrate specificity of lentil lectin, we provide a basis for the observed broad spectrum anti-SARS-CoV-2 activity. Lentil lectin showed weak haemagglutination activity at 1 mg/mL and no cytotoxicity activity, and no weight loss was found in single injection mouse experiment. This report provides the first evidence that lentil lectin strongly inhibit infection of SARS-COV-2 variants, which should provide valuable insights for developing future anti-SARS-CoV-2 strategies.
In this paper, we investigate the effects of ambient air pollution (AAP) on the spread of influenza in an AAP-dependent dynamic influenza model. The value of this study lies in two aspects. ...Mathematically, we establish the threshold dynamics in the term of the basic reproduction number $ \mathcal{R}_0 $: If $ \mathcal{R}_0 < 1 $, the disease will go to extinction, while if $ \mathcal{R}_0 > 1 $, the disease will persist. Epidemiologically, based on the statistical data in Huaian, China, we find that, in order to control the prevalence of influenza, we must increase the vaccination rate, the recovery rate and the depletion rate, and decrease the rate of the vaccine wearing off, the uptake coefficient, the effect coefficient of AAP on transmission rate and the baseline rate. To put it simply, we must change our traveling plan and stay at home to reduce the contact rate or increase the close-contact distance and wear protective masks to reduce the influence of the AAP on the influenza transmission.
The synthesis of allenyl boronates is an important yet challenging topic in organic synthesis. Reported herein is an NHC‐gold‐catalyzed 1,3‐H shift toward allenyl boronates synthesis from simple ...propargylic B(MIDA)s. Mechanistic studies suggest dual roles of the boryl moiety in the reaction: to activate the substrate for isomerization and at the same time, to prevent the allene product from further isomerization. These effects should be a result of α‐anion stabilization and α‐cation destabilization conferred by the B(MIDA) moiety, respectively. The NHC‐Au catalyst, which is commercially available, is also found to be reactive in alkyne‐to‐1,3‐diene isomerization reactions in an atom‐economic and base‐free manner.
An NHC‐gold‐catalyzed 1,3‐H shift toward allenyl boronates synthesis from simple propargylic B(MIDA)s is reported. Mechanistic studies reveal dual roles of the boryl moiety in the reaction: to activate the substrate for isomerization and to prevent the allene product from further isomerization. These effects should be a result of α‐anion stabilization and α‐cation destabilization conferred by the B(MIDA) moiety, respectively.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
To elucidate current domestic factors influencing pharmacogenomics (PGx) implementation and its future in China, we conducted a questionnaire survey on PGx applications and testing. A ...questionnaire-based survey was created on the popular online professional survey platform "Wenjuanxing" (www.wjx.cn) and performed
the social media platform WeChat. Among 422 participants, there were physicians (27.7%), pharmacists (31.3%), and researchers (41.0%). We found that less than 50% of physicians were aware of the importance of PGx in drug therapy, while over 50% of pharmacists and researchers recognized the importance. Only 38.5% of physicians, 40.9% of pharmacists, and 55.5% of researchers concurred that PGx analysis could lower the economic burdens for patients. However, most of the responders affirmed that PGx should be effectively implemented in clinical practices. A lack of sector standards, a lack of clinical research, and a lack of guidelines were found to be the major factors for hindering PGx clinical application. Among drugs associated with PGx assays, the most common were warfarin and clopidogrel. Although PGx research has advanced rapidly in recent years in mainland China, the clinical implementation of PGx has a long way to go.
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