Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in late 2019, and the outbreak rapidly evolved into the current coronavirus disease pandemic. SARS-CoV-2 is a respiratory virus ...that causes symptoms similar to those caused by influenza A and B viruses. On July 2, 2020, the US Food and Drug Administration granted emergency use authorization for in vitro diagnostic use of the Influenza SARS-CoV-2 Multiplex Assay. This assay detects influenza A virus at 102.0, influenza B virus at 102.2, and SARS-CoV-2 at 100.3 50% tissue culture or egg infectious dose, or as few as 5 RNA copies/reaction. The simultaneous detection and differentiation of these 3 major pathogens increases overall testing capacity, conserves resources, identifies co-infections, and enables efficient surveillance of influenza viruses and SARS-CoV-2.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Finding a solution for air species contamination of atmospheric pressure plasmas in plasma medical treatment is a major task for the new field of plasma medicine. Several approaches use complex ...climate chambers to control the surrounding atmosphere. In this paper, ambient species are excluded in plasma-human-skin-cell treatment by ensheathing the plasma jet effluent with a shielding gas. Not only does this gas curtain protect the plasma jet effluent from inflow of air species but it also, more importantly, allows controlling the effluent reactive species composition by adjusting the mixture of the shielding gas. In the present investigations, the mixture of nitrogen to oxygen within the gas curtain around an argon atmospheric pressure plasma jet (kinpen) is varied. The resulting reactive plasma components produced in the jet effluent are thus either oxygen or nitrogen dominated. With this gas curtain, the effect of reactive oxygen species (ROS) and reactive nitrogen species (RNS) on the cell viability of indirectly plasma-treated HaCaT skin cells is studied. This human keratinocyte cell line is an established standard for a skin model system. The cell viability is determined by a fluorometric assay, where metabolically active cells transform nonfluorescent resazurin to the highly fluorescent resorufin. Plasma jet and gas curtain are characterized by numerical flow simulation as well as by optical emission spectroscopy. The generation of nitrite within the used standard cell culture medium serves as a measure for generated RNS. Measurements with the leukodye dichlorodihydrofluorescein diacetate show that, despite a variation of the shielding gas mixture, the total amount of generated reactive oxygen plus nitrogen species is constant. It is shown that a plasma dominated by RNS disrupts cellular growth less than a ROS-dominated plasma.
The influence of ambient air species is an ever-present problem for atmospheric pressure plasma jet applications. In particular, applications where the plasma-induced effects are extremely sensitive ...to specific types of ambient species (oxygen, nitrogen, humidity) - as, for example, in plasma medicine - require concepts to exclude or to control ambient species flux into the jet effluent that go beyond an environmental control via process chambers or even vacuum systems. In this paper, we demonstrate how to eliminate ambient species influence on effluent chemistry by ensheathing the effluent. With a designed shielding gas composition, we control the species flowing into the jet effluent and thus control the effluent chemistry. The proposed approach can be applied to the majority of possible jet plasma sources. Flow simulations as well as VUV-absorption spectroscopy measurements prove the gas curtain to be effective in shielding the jet gas from ambient species and show that a control of reactive species within the jet effluent is possible. On the example of plasma treatment of a NaCl solution, we demonstrate that, by adjusting the shielding gas composition, the generation of nitrite and nitrate in the solution can be finely controlled.
The influence of ambient air species especially humidity is an ever-present challenge for atmospheric pressure plasma jet applications. Especially, where the plasma-induced effects are extremely ...sensitive to humidity, such as in the field of plasma medicine, an understanding of the influence of ambient species diffusion on plasma chemistry and on reactive component composition is crucial. In this paper, we investigate the influence of ambient humidity versus feed gas humidity on the production of reactive components by atmospheric pressure plasma jets. By the use of a shielding gas curtain, we control the surrounding atmosphere around the active effluent region of the investigated argon RF-plasma jet (kinpen) and control the gas humidity of the ambient gas. By quantum cascade laser absorption spectroscopy and by Fourier transformed infrared (IR) absorption spectroscopy, the effect of diffusing surrounding molecular species on the chemistry of the long-living reactive oxygen species is investigated. Mechanisms of H 2 O 2 and O 3 production are studied. In this paper, we have quantified the influence that ambient species, namely, water molecules, have on the reactive species' generation in the gas phase. It is shown that the effect of ambient humidity is important for the long-living species production, feed gas humidity, however, has the much stronger effect. Finally, with the focus of applications in plasma medicine, the cell viability of human skin cells (HaCaT keratinocytes) as a function of feed gas and ambient gas humidity is compared.
Based on a capacitively coupled plasma jet concept, an enhanced atmospheric pressure plasma jet setup for endoscopic applications is presented. Besides the favourable features of small dimension, ...flexibility and ability to operate in hollow bodies, new approaches for low patient leakage current, enhanced biological efficacy and reduced material erosion are subject of this work. It is found that a combination of neon feed gas, CO2 shielding gas and a current limited high voltage supply gives the best bactericidal results and, at the same time, reduces material erosion as well as patient leakage current.
Peroxynitrite (ONOO−) and peroxynitrous acid (ONOOH) are known as short acting reactive species with nitrating and oxidative properties, which are associated with their antimicrobial effect. However, ...to the best of our knowledge, ONOOH/ONOO- are not yet used as antimicrobial actives in practical applications. The aim is to elucidate if ONOOH generated in situ from acidified hydrogen peroxide (H2O2) and sodium nitrite (NaNO2) may serve as an antimicrobial active in disinfectants. Therefore, the dose-response relationship and mutagenicity are investigated. Antimicrobial efficacy was investigated by suspension tests and mutagenicity by the Ames test. Tests were conducted with E. coli. For investigating the dose-response relationship, pH values and concentrations of H2O2 and NaNO2 were varied. The antimicrobial efficacy is correlated to the dose of ONOOH, which is determined by numerical computations. The relationship can be described by the efficacy parameter W, corresponding to the amount of educts consumed during exposure time. Sufficient inactivation was observed whenever W ≥ 1 mM, yielding a criterion for inactivation of E. coli by acidified H2O2 and NaNO2. No mutagenicity of ONOOH was noticed. While further investigations are necessary, results indicate that safe and effective usage of ONOOH generated from acidified H2O2 and NaNO2 as a novel active in disinfectants is conceivable.
Plasma medicine and also decontamination of bacteria with physical plasmas is a promising new field of life science with huge interest especially for medical applications. Despite numerous successful ...applications of low temperature gas plasmas in medicine and decontamination, the fundamental nature of the interactions between plasma and microorganisms is to a large extent unknown. A detailed knowledge of these interactions is essential for the development of new as well as for the enhancement of established plasma‐treatment procedures. In the present work we introduce for the first time a growth chamber system suitable for low temperature gas plasma treatment of bacteria in liquid medium. We have coupled the use of this apparatus to a combined proteomic and transcriptomic analyses to investigate the specific stress response of Bacillus subtilis 168 cells to treatment with argon plasma. The treatment with three different discharge voltages revealed not only effects on growth, but also clear evidence of cellular stress responses. B. subtilis suffered severe cell wall stress, which was made visible also by electron microscopy, DNA damages and oxidative stress as a result of exposure to plasma. These biological findings were supported by the detection of reactive plasma species by OES measurements.
Gentle sanitation of fresh fruits and vegetables is highly demanded. Currently used methods lead to losses in product amounts and quality. Furthermore, these methods go along with high costs and ...chemical residues. One reason for such problems is microbial contamination. Due to the fact that conventional decontamination processes are not suitable for preservation of fresh produce, alternatives such as plasma technology can be helpful. Three different artificial specimen and seeds of Brassica napus were contaminated with endospores of Bacillus atrophaeus and afterwards plasma treated directly with DBD plasma and indirectly with microwave plasma processed air. After a treatment time of 15 minutes reduction rates between 0.5 and 5.2 log were achieved. The viability of seeds was not affected. The advantages of plasma and promising results offer a wide range of possible uses in food industry.
The antimicrobial efficacy of a dielectric barrier discharge (DBD) and a microwave plasma setup against Bacillus atrophaeus spores on biological and non‐biological surfaces is investigated. Moreover, the establishment of a non‐biological specimen for the comparability of different plasma techniques is shown. The decontamination efficiency raised up to 5.2 log cfu/specimen by plasma treatment.
Replication of influenza A virus (IAV) from negative-sense viral RNA (vRNA) requires the generation of positive-sense RNA (+RNA). Most molecular assays, such as conventional real-time reverse ...transcriptase PCR (rRT-PCR), detect total RNA in a sample without differentiating vRNA from +RNA. These assays are not designed to distinguish IAV infection versus exposure of an individual to an environment enriched with IAVs but wherein no viral replication occurs. We therefore developed a strand-specific hybridization (SSH) assay that differentiates between vRNA and +RNA and quantifies relative levels of each RNA species. The SSH assay exhibited a linearity of 7 logs with a lower limit of detection of 6.0 × 10
copies of molecules per reaction. No signal was detected in samples with a high load of nontarget template or influenza B virus, demonstrating assay specificity. IAV +RNA was detected 2 to 4 h postinoculation of MDCK cells, whereas synthesis of cold-adapted IAV +RNA was significantly impaired at 37°C. The SSH assay was then used to test IAV rRT-PCR positive nasopharyngeal specimens collected from individuals exposed to IAV at swine exhibitions (
= 7) or while working at live bird markets (
= 2). The SSH assay was able to differentiate vRNA and +RNA in samples collected from infected, symptomatic individuals versus individuals who were exposed to IAV in the environment but had no active viral replication. Data generated with this technique, especially when coupled with clinical data and assessment of seroconversion, will facilitate differentiation of actual IAV infection with replicating virus versus individuals exposed to high levels of environmental contamination but without virus infection.
An innovative device capable of generating a cold atmospheric pressure plasma inside a 5 m long flexible tube with 2 mm inner diameter is presented. In order to analyze the inner‐tube plasma, optical ...emission spectroscopy in the (vacuum) ultraviolet spectral range and Fourier transformed infrared spectroscopy were performed. By admixing small concentrations of nitrogen and oxygen to the standard argon gas flow rate of 1.5 slm, a drastically change in the plasma composition was observed. Additionally, it is possible to form a jet‐like plasma at the end of the tube. The microbicidal efficacy of the inner‐tube plasma and the jet‐like plasma was shown for Bacillus atrophaeus spores.
In this paper a setup is presented, to generate a DBD inside a long, flexible and thermo labile tube with the purpose to decontaminate the inner tube walls. The main application for these modified tubes is the implementation as biopsy channels in endoscopes, which are highly contaminated and difficult to sterilize. Besides decontamination of the inner tube it is also possible to ignite a jet‐like discharge at the tube end.
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