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31.
Matthias A. Reinhard Wolfram Regen Chiara Baglioni Christoph Nissen Bernd Feige Jürgen Hennig Dieter Riemann Kai Spiegelhalder 《PloS one》2014,9(10)
BackgroundNormal sleep continuity and architecture show remarkable inter-individual variability. Previous studies suggest that brain morphology may explain inter-individual differences in sleep variables.MethodThirty-eight healthy subjects spent two consecutive nights at the sleep laboratory with polysomnographic monitoring. Furthermore, high-resolution T1-weighted MRI datasets were acquired in all participants. EEG sleep recordings were analyzed using standard sleep staging criteria and power spectral analysis. Using the FreeSurfer software for automated segmentation, 174 variables were determined representing the volume and thickness of cortical segments and the volume of subcortical brain areas. Regression analyses were performed to examine the relationship with polysomnographic and spectral EEG power variables.ResultsThe analysis did not provide any support for the a-priori formulated hypotheses of an association between brain morphology and polysomnographic variables. Exploratory analyses revealed that the thickness of the left caudal anterior cingulate cortex was positively associated with EEG beta2 power (24–32 Hz) during REM sleep. The volume of the left postcentral gyrus was positively associated with periodic leg movements during sleep (PLMS).ConclusionsThe function of the anterior cingulate cortex as well as EEG beta power during REM sleep have been related to dreaming and sleep-related memory consolidation, which may explain the observed correlation. Increased volumes of the postcentral gyrus may be the result of increased sensory input associated with PLMS. However, due to the exploratory nature of the corresponding analyses, these results have to be replicated before drawing firm conclusions. 相似文献
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Comparative measurements of bacterial total counts and volumes of flow cytometry (FCM), transmission electron (TEM), and epifluorescence microscopy (EFM), were undertaken during a four week mesocosm experiment. Total counts of bacteria measured by TEM, EFM, and FCM were in the range of 1 · 106−6 cells ml−1, 1 · 106−3 · 1016 cells ml−1, and 5 · 105 cells ml−1 respectively. The mean volume of the bacterial community, measured by means of EFM and TEM, increased from 0.12–0.15 μm3 at the start of the experiment to 0.39–0.53 μm3 at the end. Generally, there was good agreement between the two methods and regression analyses gave r = 0.87 (p < < 0.01) for cell volume and r = 0.97 (p < < 0.01) for cell number. DAPI stained bacteria with volumes less than 0.2 μm3 were not detected by flow cytometry and these were generally an order of magnitude lower than counts made by TEM and EFM. For samples where the mean bacterial cell volume was longer than 0.3 μm3, all three methods were in agreement both with respect to counts and volume estimates. 相似文献
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The 480/665 nm absorption ratio for pigment extracts was evaluatedas an indicator of nutrient limitation using freshwater planktoncommunities and a mesocosm approach. The mesocosm design wasused to create various nutrient regimes for the phytoplanktoncommunities, and nutrient limitation was detected by means ofgrowth response assays (14 fixation and pigment increase followingaddition of nutrients) and the 480/665 ratio. Results from fourperiods in 1993 and one period in 1994 showed that high 480/665ratios (indicative of nutrient limitation) were only found atchlorophyll a concentrations <20 µg I1, wherenutrient limitation was not detected. Periods with potentialnutrient limitation exhibited low 480/665 ratios. Consequently,the absolute values of the 480/665 ratio could not be used topredict nutrient limitation. However, when nutrients were addedto nutrient- limited phytoplankton communities in growth responseassays, the ratio decreased, indicating that the 480/665 ratiocan be used as a relative index to detect nutrient limitationin bioassays. 相似文献
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Alexandra K. Nothstein Elisabeth Eiche Michael Riemann Peter Nick Lenny H. E. Winkel J?rg G?ttlicher Ralph Steininger Rita Brendel Matthias von Brasch Gabriele Konrad Thomas Neumann 《PloS one》2016,11(4)
Up to 1 billion people are affected by low intakes of the essential nutrient selenium (Se) due to low concentrations in crops. Biofortification of this micronutrient in plants is an attractive way of increasing dietary Se levels. We investigated a promising method of Se biofortification of rice seedlings, as rice is the primary staple for 3 billion people, but naturally contains low Se concentrations. We studied hydroponic Se uptake for 0–2500 ppb Se, potential phyto-toxicological effects of Se and the speciation of Se along the shoots and roots as a function of added Se species, concentrations and other nutrients supplied. We found that rice germinating directly in a Se environment increased plant-Se by factor 2–16, but that nutrient supplementation is required to prevent phyto-toxicity. XANES data showed that selenite uptake mainly resulted in the accumulation of organic Se in roots, but that selenate uptake resulted in accumulation of selenate in the higher part of the shoot, which is an essential requirement for Se to be transported to the grain. The amount of organic Se in the plant was positively correlated with applied Se concentration. Our results indicate that biofortification of seedlings with selenate is a successful method to increase Se levels in rice. 相似文献
36.
H P Riemann J A Howarth R Ruppanner C E Franti D E BEHYMER 《Journal of wildlife diseases》1975,11(2):272-276
The prevalence of antibodies to Toxoplasma gondii was investigated among five species of wild carnivores in Norther Ccalifornia. The highest prevalence was among bobcats (Lynx rufus), with 15 of 21 tested being serologically positive. Other results included serological evidence of toxoplasmosis in two of seven raccoons (Procyon lotor), one of three badgers (taxidea taxus) and two of three coyotes (Canis latrans). Two gray foxes (Urocyon cinereoargenteus) were serologically negative. Oone badger with an indirect hemagglutination antibody titer of 1:8192 was found to harbor T. gondii in its brain tissues. 相似文献
37.
Despite a high Ca2+-permeability of the P2Z receptor in human B lymphocytes, extracellular ATP4has only a minor effect on global [Ca2+]i. The aim of this study was to reveal the mechanisms responsible for this discrepancy. We investigated the relationship between ATP4−-application, Cai2-response, membrane current and membrane potential in two human B cell lines and in human tonsillar B cells. This was achieved by a combination of FACS- and voltage clamp measurements and the usage of appropriate voltage- and Ca2-sensitive fluorescent dyes. ATP4-induced changes in whole-cell current and [Ca2]iwere blocked by extracellular as well as intracellular Na+. Under current clamp conditions, ATP4−-induced Na+-entry diminished the Ca2+entry via reduction of the driving force. A substantial increase in [Ca2+]iinduced by ATP4−was only observed in Na+-free solutions.The pathway of signal transduction activated by ATP4via P2Z receptor of human B lymphocytes under physiological conditions seems not to operate by an increase in the global intracellular Ca2-concentration, but rather by the depolarization of the cell membrane as a result of the Na+-influx. 相似文献
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