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71.
Both the current and newly proposed safety guidelines for local human exposure to millimeter-wave frequencies aim at restricting the maximum local temperature increase in the skin to prevent tissue damage. In this study, we show that the application of the current and proposed limits for pulsed fields can lead to a temperature increase of 10°C for short pulses and frequencies between 6 and 30 GHz. We also show that the proposed averaging area of 4 cm2, that is greatly reduced compared with the current limits, does not prevent high-temperature increases in the case of narrow beams. A realistic Gaussian beam profile with a 1 mm radius can result in a temperature increase about 10 times higher than the 0.4°C increase the same averaged power density would produce for a plane wave. In the case of pulsed narrow beams, the values for the time and spatial-averaged power density allowed by the proposed new guidelines could result in extreme temperature increases. Bioelectromagnetics. 2020;41:164–168. © 2019 Bioelectromagnetics Society. 相似文献
72.
Niels Schaft Verena Wellner Christian Wohn Gerold Schuler Jan Dörrie 《Cancer immunology, immunotherapy : CII》2013,62(12):1769-1780
RNA transfection is a standard method to load dendritic cells (DC) with antigen for therapeutic cancer vaccination. While electroporation yields high transfection efficiency and satisfying expression levels, lipofection results in only few cells expressing high amounts of antigen. We compared antigen loading of human monocyte-derived DC by MelanA RNA electroporation and lipofection. No differences in phenotype or migrational capacity were detected, but lipofected DC induced stronger cytokine secretion by antigen-specific T cells and were superior in priming and boosting of MelanA-specific CD8+ T cells. Interestingly, T cells stimulated with the differently transfected DC did not differ in their functional avidity. To determine whether the amount of antigen per cell is indeed responsible for the superiority of the lipofected DC, we increased the amount of MelanA RNA fivefold and mixed those DC with mock-electroporated ones to mimic the antigen distribution of lipofected cells. This significantly improved the stimulatory capacity, indicating that indeed the amount of antigen per cell seems to be the responsible feature for the observed superiority of lipofected DCs. These data suggest that a few DC that express high amounts of antigen are more immunogenic than many DC expressing lower amounts, although this needs to be tested in a two-armed immunogenicity trial. 相似文献
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Arctic plants and herbivores are subject to ongoing climatic changes that are more rapid and extreme than elsewhere on the planet, and thus it is pivotal to understand the arctic plant-herbivore interactions in a global change context. We examined how infestation by an eriophyoid gall mite affects the circumpolar shrub Salix arctica, and how the effects vary across vegetation types. Specifically, we compared multiple leaf characteristics (leaf area, biomass, nutrient levels, δ15N and δ13C, and stress and performance of the photosynthetic apparatus) of infested leaves to those of un-infested leaves. Furthermore, we examined how altered environmental conditions, here experimentally manipulated levels of temperature, water and nutrients, shading, and UV-B radiation, affect the prevalence, density, and intensity of gall mite infestation and its impacts on S. arctica. Infested leaves were smaller in area and biomass and had lower nitrogen and carbon pools. However, their carbon concentration was higher, possibly because the galls acted as carbon sinks. The smaller photosynthetic area and lower nutrient content caused increased stress on the photosynthetic apparatus in infested leaves. The remaining leaf tissue responded with a higher photosynthetic performance, although there were indications of a general reduction in photosynthesis. Female leaves were more affected than male leaves. The experimental manipulations of environmental conditions did not affect the gall prevalence, density, or intensity on S. arctica leaves. Rather, plants responded positively to the treatments, reducing the effects of the galls to in-significance. This suggests a higher tolerance and defense against gall mites under future climate conditions. 相似文献
75.
Anne Krog Tonje Marita Bjerkan Heggeset Trond Erling Ellingsen Trygve Brautaset 《Applied and environmental microbiology》2013,79(17):5321-5328
Bacillus methanolicus wild-type strain MGA3 secretes 59 g/liter−1 of l-glutamate in fed-batch methanol cultivations at 50°C. We recently sequenced the MGA3 genome, and we here characterize key enzymes involved in l-glutamate synthesis and degradation. One glutamate dehydrogenase (GDH) that is encoded by yweB and two glutamate synthases (GOGATs) that are encoded by the gltAB operon and by gltA2 were found, in contrast to Bacillus subtilis, which has two different GDHs and only one GOGAT. B. methanolicus has a glutamine synthetase (GS) that is encoded by glnA and a 2-oxoglutarate dehydrogenase (OGDH) that is encoded by the odhAB operon. The yweB, gltA, gltB, and gltA2 gene products were purified and characterized biochemically in vitro. YweB has a low Km value for ammonium (10 mM) and a high Km value for l-glutamate (250 mM), and the Vmax value is 7-fold higher for l-glutamate synthesis than for the degradation reaction. GltA and GltA2 displayed similar Km values (1 to 1.4 mM) and Vmax values (4 U/mg) for both l-glutamate and 2-oxoglutarate as the substrates, and GltB had no effect on the catalytic activities of these enzymes in vitro. Complementation assays indicated that GltA and not GltA2 is dependent on GltB for GOGAT activity in vivo. To our knowledge, this is the first report describing the presence of two active GOGATs in a bacterium. In vivo experiments indicated that OGDH activity and, to some degree, GOGAT activity play important roles in regulating l-glutamate production in this organism. 相似文献
76.
In order to elucidate the phylogeny and evolutionary history of the Bacillariaceae we conducted a phylogenetic analysis of 42 species (sequences were determined from more than two strains of many of the Pseudo-nitzschia species) based on the first 872 base pairs of nuclear-encoded large subunit (LSU) rDNA, which include some of the most variable domains. Four araphid genera were used as the outgroup in maximum likelihood, parsimony and distance analyses. The phylogenetic inferences revealed the Bacillariaceae as monophyletic (bootstrap support ≥90%). A clade comprising Pseudo-nitzschia, Fragilariopsis and Nitzschia americana (clade A) was supported by high bootstrap values (≥94%) and agreed with the morphological features revealed by electron microscopy. Data for 29 taxa indicate a subdivision of clade A, one clade comprising Pseudo-nitzschia species, a second clade consisting of Pseudo-nitzschia species and Nitzschia americana, and a third clade comprising Fragilariopsis species. Pseudo-nitzschia as presently defined is paraphyletic and emendation of the genus is probably needed. The analyses suggested that Nitzschia is not monophyletic, as expected from the great morphological diversity within the genus. A cluster characterized by possession of detailed ornamentation on the frustule is indicated. Eighteen taxa (16 within the Bacillariaceae) were tested for production of domoic acid, a neurotoxic amino acid. Only P. australis, P. multiseries and P. seriata produced domoic acid, and these clustered together in all analyses. Since Nitzschia navis-varingica also produces domoic acid, but is distantly related to the cluster comprising the Pseudo-nitzschia domoic acid producers, it is most parsimonious to suggest that the ability of species in the Bacillariaceae to produce domoic acid has evolved at least twice. 相似文献
77.
The fact that membrane proteins are notoriously difficult to analyse using standard protocols for atomic-resolution structure determination methods have motivated adaptation of these techniques to membrane protein studies as well as development of new technologies. With this motivation, liquid-state nuclear magnetic resonance (NMR) has recently been used with success for studies of peptides and membrane proteins in detergent micelles, and solid-state NMR has undergone a tremendous evolution towards characterization of membrane proteins in native membrane and oriented phospholipid bilayers. In this mini-review, we describe some of the technological challenges behind these efforts and provide examples on their use in membrane biology. 相似文献
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Markus Ernstberger Pascal Boeswetter Tobias Baselt Frank Ebert Fabiola Basan Hanno Steinke Niels Hammer Ronny Grunert Peter Hartmann 《Journal of biophotonics》2013,6(4):310-313
Thin slices of human tissues are characterized concerning reflection and transmission in a wavelength range from 400 to 1700 nm. The results are primarily useful to find a wavelength for the detection of subjacent blood vessels during surgical procedures, especially neurological surgery. The measurements have been conducted using a customized measuring station, utilizing two halogen bulb lamps and two spectrometers. This paper focuses on creating a data base with the optical properties of artery, brain, bone, nasal mucosa, and nerve. The spectral distributions are compared among each other, similarities and differences are pointed out. Each tissue has got unique spectral characteristics, whereas typical absorption bands can be found in the overall tissues, especially hemoglobin and water absorption bands. The reflectivity maxima are typically located in the red or near‐infrared. All the transmission maxima are located between 1075 nm and 1100 nm. The measurements have been conducted at the Institute of Anatomy at the University of Leipzig. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献