Point-of-care (POC) methods currently available for detecting SARS-CoV-2 infections still lack accuracy. Here, we report the development of a highly sensitive electrochemical immunoassay capable of ...quantitatively detecting the presence of the SARS-CoV-2 virus in patient nasopharyngeal samples using stencil-printed carbon electrodes (SPCEs) functionalized with capture antibodies targeting the SARS-CoV-2 nucleocapsid protein (N protein). Samples are added to the electrode surface, followed by horseradish peroxidase (HRP)-conjugated detection antibodies also targeting the SARS-CoV-2 N protein. The concentration of the virus in samples is quantified using chronoamperometry in the presence of 3,3′5,5′-tetramethylbenzidine. Limits of detection equivalent to less than 50 plaque forming units/mL (PFU/mL) were determined with virus sample volumes of 20 μL. No cross-reactivity was detected with the influenza virus and other coronavirus N proteins. Patient nasopharyngeal samples were tested as part of a proof-of-concept clinical study where samples were also tested using the gold-standard real-time quantitative polymerase chain reaction (RT-qPCR) method. Preliminary results from a data set of 22 samples demonstrated a clinical specificity of 100% (n = 9 negative samples according to RT-qPCR) and a clinical sensitivity of 70% for samples with RT-PCR cycle threshold (Ct) values under 30 (n = 10) and 100% for samples with Ct values under 25 (n = 5), which complies with the World Health Organization (WHO) criteria for POC COVID-19 diagnostic tests. Our functionalized SPCEs were also validated against standard plaque assays, and very good agreement was found between both methods (R 2 = 0.9993, n = 6), suggesting that our assay could be used to assess patient infectivity. The assay currently takes 70 min from sampling to results.
The Klebsiella pneumoniae carbapenem (KPC) β-lactamase occurs in Enterobacteriaceae and can confer resistance to all β-lactam agents including carbapenems. The enzyme may confer low-level carbapenem ...resistance, and the failure of susceptibility methods to identify this resistance has been reported. Automated and nonautomated methods for carbapenem susceptibility were evaluated for identification of KPC-mediated resistance. Ertapenem was a more sensitive indicator of KPC resistance than meropenem and imipenem independently of the method used. Carbapenemase production could be confirmed with the modified Hodge test.
Warfarin is a widely used anticoagulant with a narrow therapeutic index and large interpatient variability in the dose required to achieve target anticoagulation. Common genetic variants in the ...cytochrome P450–2C9 (CYP2C9) and vitamin K–epoxide reductase complex (VKORC1) enzymes, in addition to known nongenetic factors, account for ~50% of warfarin dose variability. The purpose of this article is to assist in the interpretation and use of CYP2C9 and VKORC1 genotype data for estimating therapeutic warfarin dose to achieve an INR of 2–3, should genotype results be available to the clinician. The Clinical Pharmacogenetics Implementation Consortium (CPIC) of the National Institutes of Health Pharmacogenomics Research Network develops peer–reviewed gene–drug guidelines that are published and updated periodically on http://www.pharmgkb.org based on new developments in the field.1
Clinical Pharmacology & Therapeutics (2011) 90 4, 625–629. doi:10.1038/clpt.2011.185
Southeast Brazil is a neotropical region composed of a mosaic of different tropical habitats and mountain chains, which allowed for the formation of bird-rich communities with distinct ecological ...niches. Although this region has the potential to harbor a remarkable variety of avian parasites, there is a lack of information about the diversity of malarial parasites. We used molecular approaches to characterize the lineage diversity of Plasmodium and Haemoproteus in bird communities from three different habitats in southeast Brazil based on the prevalence, richness and composition of lineages. We observed an overall prevalence of 35.3%, with a local prevalence ranging from 17.2% to 54.8%. Moreover, no significant association between prevalence and habitat type could be verified (p>0.05). We identified 89 Plasmodium and 22 Haemoproteus lineages, with 86% of them described for the first time here, including an unusual infection of a non-columbiform host by a Haemoproteus (Haemoproteus) parasite. The composition analyses of the parasite communities showed that the lineage composition from Brazilian savannah and tropical dry forest was similar, but it was different from the lineage composition of Atlantic rainforest, reflecting the greater likeness of the former habitats with respect to seasonality and forest density. No significant effects of habitat type on lineage richness were observed based on GLM analyses. We also found that sites whose samples had a greater diversity of bird species showed a greater diversity of parasite lineages, providing evidence that areas with high bird richness also have high parasite richness. Our findings point to the importance of the neotropical region (southeast Brazil) as a major reservoir of new haemosporidian lineages.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Electromagnetic ion cyclotron (EMIC) waves play important roles in particle loss processes in the magnetosphere. Determining the evolution of EMIC waves as they propagate and how this evolution ...affects wave‐particle interactions requires accurate knowledge of the wave vector, k. We present a technique using the curl of the wave magnetic field to determine k observationally, enabled by the unique configuration and instrumentation of the Magnetospheric MultiScale (MMS) spacecraft. The wave curl analysis is demonstrated for synthetic arbitrary electromagnetic waves with varying properties typical of observed EMIC waves. The method is also applied to an EMIC wave interval observed by MMS on October 28, 2015. The derived wave properties and k from the wave curl analysis for the observed EMIC wave are compared with the Waves in Homogenous, Anisotropic, Multi‐component Plasma (WHAMP) wave dispersion solution and with results from other single‐ and multi‐spacecraft techniques. We find good agreement between k from the wave curl analysis, k determined from other observational techniques, and k determined from WHAMP. Additionally, the variation of k due to the time and frequency intervals used in the wave curl analysis is explored. This exploration demonstrates that the method is robust when applied to a wave containing at least 3–4 wave periods and over a rather wide frequency range encompassing the peak wave emission. These results provide confidence that we are able to directly determine the wave vector properties using this multi‐spacecraft method implementation, enabling systematic studies of EMIC wave k properties with MMS.
Plain Language Summary
Waves generated within space plasmas play important roles in accelerating, heating, and depleting charged particles in Earth’s magnetosphere. The wave vector, k, mathematically relates the wavelength, direction of wave motion, and wave type to the conditions that produced it. This also tells us if a wave can interact with electrons and ions in ways that will affect the radiation belts. A key problem in understanding waves in space is that k is very difficult to determine observationally. We present a method for calculating k using Magnetospheric Multiscale (MMS) mission data. The “wave curl analysis” uses magnetic field measurements from all four MMS spacecraft to determine the electric current of the magnetic field fluctuations, which allows for direct calculation of k. We test the method on mathematically generated waveforms with properties that mimic electromagnetic ion cyclotron (EMIC) waves previously observed by MMS. We then applied this method to EMIC wave observations and compared the results to theoretical predictions and other methods for estimating k from spacecraft measurements. The wave curl analysis opens up a new way to use MMS to understand how EMIC waves are generated, how they travel and evolve, and how they affect plasma in the near‐Earth space environment.
Key Points
The wave curl analysis is a new implementation of determining k using observed wave magnetic field and associated current density
The wave curl analysis reliably determines k for both synthetic waves and Magnetospheric MultiScale observations of electromagnetic ion cyclotron waves
The calculated k is robust relative to time and frequency ranges used in the analysis, and agrees well with linear dispersion theory
The interferon-induced enzymes 2′-5′-oligoadenylate synthetase (OAS) and RNase L are key components of innate immunity involved in sensory and effector functions following viral infections. Upon ...binding target RNA, OAS is activated to produce 2′-5′-linked oligoadenylates (2-5A) that activate RNase L, which then cleaves single-stranded self and non-self RNA. Modified nucleosides that are present in cellular transcripts have been shown to suppress activation of several RNA sensors. Here, we demonstrate that in vitro transcribed, unmodified RNA activates OAS, induces RNase L-mediated ribosomal RNA (rRNA) cleavage and is rapidly cleaved by RNase L. In contrast, RNA containing modified nucleosides activates OAS less efficiently and induces limited rRNA cleavage. Nucleoside modifications also make RNA resistant to cleavage by RNase L. Examining translation in RNase L−/− cells and mice confirmed that RNase L activity reduces translation of unmodified mRNA, which is not observed with modified mRNA. Additionally, mRNA containing the nucleoside modification pseudouridine is translated longer and has an extended half-life. The observation that modified nucleosides in RNA reduce 2-5A pathway activation joins OAS and RNase L to the list of RNA sensors and effectors whose functions are limited when RNA is modified, confirming the role of nucleoside modifications in suppressing immune recognition of RNA.
Electromagnetic ion cyclotron (EMIC) waves at large L shells were observed away from the magnetic equator by the Magnetospheric MultiScale (MMS) mission nearly continuously for over four hours on 28 ...October 2015. During this event, the wave Poynting vector direction systematically changed from parallel to the magnetic field (toward the equator), to bidirectional, to antiparallel (away from the equator). These changes coincide with the shift in the location of the minimum in the magnetic field in the southern hemisphere from poleward to equatorward of MMS. The local plasma conditions measured with the EMIC waves also suggest that the outer magnetospheric region sampled during this event was generally unstable to EMIC wave growth. Together, these observations indicate that the bidirectionally propagating wave packets were not a result of reflection at high latitudes but that MMS passed through an off‐equator EMIC wave source region associated with the local minimum in the magnetic field.
Plain Language Summary
Electromagnetic ion cyclotron (EMIC) waves are a fundamental plasma instability in space environments. In near‐Earth space, these waves act as one mechanism for energetic electrons in the radiation belts to be lost to the atmosphere. Because EMIC waves are important for the transport of energy throughout the magnetosphere, understanding where and how these waves are generated, as well as how the waves move along a magnetic field line, is necessary for understanding the full cycle of energization and loss of plasma. The two previous case studies of EMIC waves at high latitudes in the outer magnetosphere were not able to determine if the waves were generated at those high latitudes or if the wave signatures were due to reflection of the waves back toward the magnetic equator, which has important implications for waves seen from the ground. The observations presented here show EMIC waves in the outer magnetosphere away from the equator nearly continuously over several hours. Using the wave Poynting flux direction (which indicates how the waves are moving along the magnetic field), we show unambiguously for the first time that these EMIC waves are from a local source region at higher latitudes.
Key Points
Several hours of EMIC wave activity were observed off‐equator in the outer magnetosphere with plasma conditions favorable for local growth
Changes in direction of the wave Poynting vector indicate transition of source region from poleward, to local, to equatorward of spacecraft
Observations confirm association of EMIC wave source region with local minimum‐B of the field line, possibly related to Shabansky orbits
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