As one of the major approaches in combating the COVID-19 pandemics, the availability of specific and reliable assays for the SARS-CoV-2 viral genome and its proteins is essential to identify the ...infection in suspected populations, make diagnoses in symptomatic or asymptomatic individuals, and determine clearance of the virus after the infection. For these purposes, use of the quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) for detection of the viral nucleic acid remains the most valuable in terms of its specificity, fast turn-around, high-throughput capacity, and reliability. It is critical to update the sequences of primers and probes to ensure the detection of newly emerged variants. Various assays for increased levels of IgG or IgM antibodies are available for detecting ongoing or past infection, vaccination responses, and persistence and for identifying high titers of neutralizing antibodies in recovered individuals. Viral genome sequencing is increasingly used for tracing infectious sources, monitoring mutations, and subtype classification and is less valuable in diagnosis because of its capacity and high cost. Nanopore target sequencing with portable options is available for a quick process for sequencing data. Emerging CRISPR-Cas-based assays, such as SHERLOCK and AIOD-CRISPR, for viral genome detection may offer options for prompt and point-of-care detection. Moreover, aptamer-based probes may be multifaceted for developing portable and high-throughput assays with fluorescent or chemiluminescent probes for viral proteins. In conclusion, assays are available for viral genome and protein detection, and the selection of specific assays depends on the purposes of prevention, diagnosis and pandemic control, or monitoring of vaccination efficacy.
During the COVID-19 pandemics, sensitive and reliable assays for SARS-CoV-2 detection are essential for screening the population, identifying asymptomatic individuals, making diagnoses, monitoring treatment responses, and determining viral clearance. This review summarizes the principles, advantages, disadvantages, and specific applications of currently available assays for detection of the viral nucleotide, genome or proteins, as well as host antibody responses, and provide overall guidelines for selection of optimal assays for specific usage.
Glioma represents a fast proliferating and highly invasive brain tumor which is resistant to current therapies and invariably recurs. Despite some advancements in anti-glioma therapies, patients' ...prognosis remains poor. Toll-like receptors (TLRs) act as the first line of defense in the immune system being the detectors of those associated with bacteria, viruses, and danger signals. In the glioma microenvironment, TLRs are expressed on both immune and tumor cells, playing dual roles eliciting antitumoral (innate and adaptive immunity) and protumoral (cell proliferation, migration, invasion, and glioma stem cell maintenance) responses. Up to date, several TLR-targeting therapies have been developed aiming at glioma bulk and stem cells, infiltrating immune cells, the immune checkpoint axis, among others. While some TLR agonists exhibited survival benefit in clinical trials, it attracts more attention when they are involved in combinatorial treatment with radiation, chemotherapy, immune vaccination, and immune checkpoint inhibition in glioma treatment. TLR agonists can be used as immune modulators to enhance the efficacy of other treatment, to avoid dose accumulation, and what brings more interests is that they can potentiate immune checkpoint delayed resistance to PD-1/PD-L1 blockade by upregulating PD-1/PD-L1 overexpression, thus unleash powerful antitumor responses when combined with immune checkpoint inhibitors. Herein, we focus on recent developments and clinical trials exploring TLR-based treatment to provide a picture of the relationship between TLR and glioma and their implications for immunotherapy. Keywords: Glioma, Toll-like receptors, TLR-targeted therapies, Clinical trials, Immunotherapy
Few studies provide direct evidences that agricultural fiscal affects agricultural carbon intensity. This study tries to fill this gap. Using panel data of 30 provinces in China from 2005 to 2019, we ...conclude that agricultural fiscal expenditures significantly reduce agricultural carbon intensity. The result is still robust after employing the provincial agricultural leaders’ birthplace information as an instrumental variable. Further study shows that the negative effect of agricultural fiscal expenditures on agricultural carbon intensity is more pronounced in regions with less corruption and is also more visible in central, western, and inland regions than other areas. For this effect, agricultural technological improvement and structure optimization are possible channels, but not operation scale expansion. Interestingly, although agricultural fiscal expenditures reduce the local agricultural carbon intensity, neighbor regions’ carbon intensities are increased due to fiscal rivalry.
Abstract
This paper systematically studies the relation between metallicity and mass loss of massive stars. We perform one-dimensional stellar evolution simulations and build a grid of ∼2000 models ...with initial masses ranging between 11 and 60
M
⊙
and absolute metallicities
Z
between 0.00001 and 0.02. Steady-state winds, comprising hot main-sequence winds and cool supergiant winds, are the main drivers of the mass loss of massive stars in our models. We calculate the total mass loss over the stellar lifetime for each model. Our results reveal the existence of a critical metallicity
Z
c
at
Z
∼ 10
−3
, where the mass loss exhibits a dramatic jump. If
Z
>
Z
c
, massive stars tend to evolve into cool supergiants, and a robust cool wind is operational. In contrast, if
Z
<
Z
c
, massive stars usually remain as blue supergiants, wherein the cool wind is not activated and the mass loss is generally weak. Moreover, we calculate the wind feedback in a 10
5
M
⊙
star cluster with the Salpeter initial mass function. The kinetic energy released by winds does not exhibit any significant transition at
Z
c
because the wind velocity of a cool supergiant wind is low and contributes little to the kinetic energy. The effects of critical metallicity provide implications for the fates of metal-poor stars in the early universe.
To describe the characteristics of
(
) antibiotic resistance in clinical isolates from four populations.
In total, 1463
strains were examined for antibiotic resistance. Among these strains, 804 were ...isolated from treatment-naïve adults, 133 from previously treated adults, 100 from treatment-naïve children and 426 from a population who participated in a health survey (age ≥ 40 years). The minimum inhibitory concentration was determined by the E-test method.
In the treatment-naïve adult group, the resistance rates for metronidazole, clarithromycin, levofloxacin, amoxicillin, rifampicin and tetracycline were 78.4, 19.0, 23.3, 1.2, 1.7 and 2.3%, respectively. Compared with this group, the previously treated adult group had significantly higher resistance rates for metronidazole (99.2%), clarithromycin (58.3%) and levofloxacin (52.3%). In addition, the treatment-naïve children had a lower metronidazole resistance rate (46.0%) than the treatment-naïve adults. The resistance rate for clarithromycin was low in treatment-naïve patients with ages ranging from 10 to 24 years. For the strains isolated from the general population group, the resistance rates for metronidazole, clarithromycin, levofloxacin, amoxicillin, rifampicin and tetracycline were 78.6, 10.1, 25.1, 0.5, 2.1 and 0.9%, respectively. Compared with the treatment-naïve adult group, the general population group showed significant differences in clarithromycin resistance.
The resistance rates for metronidazole, clarithromycin and levofloxacin were high, especially in previously treated adults. Compared to those in treatment-naïve younger patients, the resistance rates for clarithromycin were significantly lower in treatment-naïve patients with ages ranging from 10 to 24 years and in the general population.
Agricultural pollution is extremely serious in China, and agricultural output quantity subsidy makes it even worse. This paper captures the impacts of agricultural subsidy, including quantity subsidy ...and innovation subsidy, on agricultural pollution. Agriculture output quantity, total pollution or emission, equilibrium price, consumer and producer surplus, government budget, and social welfare are all addressed in this study. The results show that emission-reducing innovation subsidy is better than quantity subsidy because it reduces the pollution from agriculture and profits for the agricultural firm are higher under innovation subsidy than under quantity subsidy. More importantly, output quantity and consumer surplus under innovation subsidy are also larger than those under quantity subsidy if the subsidy rate is not too high. This study finds that the importance of the environment to the consumer, marginal emission, and pollution tax will decrease output quantity, consumer and producer surplus and social welfare; however, agricultural subsidy increases them. Furthermore, this study indicates that innovation subsidy can alleviate the “food quantity safety and quality of environment” dilemma in agriculture.
•The effects of pollution taxes and agricultural subsidies are both captured.•Output quantity, consumer surplus, government budget, and social welfare are all addressed.•Pollution-reducing innovation subsidies are more efficient than quantity subsidies in agriculture.•A useful agricultural pollution regulation system is designed in this study.
Abstract
The geometric structure of supernova remnants (SNR) provides a clue to unveiling the pre-explosion evolution of their progenitors. Here we present an X-ray study of N103B (0509–68.7), a Type ...Ia SNR in the Large Magellanic Cloud, that is known to be interacting with dense circumstellar matter (CSM). Applying our novel method for feature extraction to deep Chandra observations, we have successfully resolved the CSM, Fe-rich ejecta, and intermediate-mass element (IME) ejecta components, and revealed each of their spatial distributions. Remarkably, the IME ejecta component exhibits a double-ring structure, implying that the SNR expands into an hourglass-shape cavity and thus forms bipolar bubbles of the ejecta. This interpretation is supported by more quantitative spectroscopy that reveals a clear bimodality in the distribution of the ionization state of the IME ejecta. These observational results can be naturally explained if the progenitor binary system had formed a dense CSM torus on the orbital plane prior to the explosion, providing further evidence that the SNR N103B originates from a single-degenerate progenitor.
One of the most promising strategies for the management of plastic waste is microbial biodegradation, but efficient degraders for many types of plastics are still lacking, including those for ...polystyrene (PS). Genomics has emerged as a powerful tool for mining environmental microbes that may have the ability to degrade different types of plastics. In this study, we use 16S rRNA sequencing to analyze the microbiomes for multiple PS samples collected from sites with different vegetation in Taiwan to reveal potential common properties between species that exhibit growth advantages on PS surfaces. Phylum enrichment analysis identified Cyanobacteria and Deinococcus-Thermus as being the most over-represented groups on PS, and both phyla include species known to reside in extreme environments and could encode unique enzymes that grant them properties suitable for colonization on PS surfaces. Investigation of functional enrichment using reference genomes of PS-enriched species highlighted carbon metabolic pathways, especially those related to hydrocarbon degradation. This is corroborated by the finding that genes encoding long-chain alkane hydroxylases such as AlmA are more prevalent in the genomes of PS-associated bacteria. Our analyses illustrate how plastic in the environment support the colonization by different microbes compared to surrounding soil. In addition, our results point to the possibility that alkane hydroxylases could confer growth advantages of microbes on PS.
Abstract
The supernova remnant (SNR) 30 Dor B is associated with the H
ii
region ionized by the OB association LH99. The complex interstellar environment has made it difficult to study the physical ...structure of this SNR. We have used Hubble Space Telescope H
α
images to identify SNR shocks and deep Chandra X-ray observations to detect faint diffuse emission. We find that 30 Dor B hosts three zones with very different X-ray surface brightnesses and nebular kinematics that are characteristic of SNRs in different interstellar environments and/or evolutionary stages. The ASKAP 888 MHz map of 30 Dor B shows counterparts to all X-ray emission features except the faint halo. The ASKAP 888 and 1420 MHz observations are used to produce a spectral index map, but its interpretation is complicated by the background thermal emission and the pulsar PSR J0537−6910's flat spectral index. The stellar population in the vicinity of 30 Dor B indicates a continuous star formation in the past 8–10 Myr. The observed very massive stars in LH99 cannot be coeval with the progenitor of 30 Dor B’s pulsar. Adopting the pulsar’s spin-down timescale, 5000 yr, as the age of the SNR, the X-ray shell would be expanding at ∼4000 km s
−1
and the post-shock temperature would be 1–2 orders of magnitude higher than that indicated by the X-ray spectra. Thus, the bright central region of 30 Dor B and the X-ray shell requires two separate SN events, and the faint diffuse X-ray halo perhaps other older SN events.
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