The neutron time-of-flight spectrometer NEAT has a long history of successful applications and is best suited to probe dynamic phenomena directly in the large time domain 10−14 – 10−10 s and on the ...length scale ranging from 0.05 to up to about 5 nm. To address user community needs for more powerful instrumental capabilities, a concept of the full upgrade of NEAT has been proposed. The upgrade started in 2010 after a rigorous internal and external selection process and resulted in 300-fold neutron count rate increase compared to NEAT′1995. Combined with new instrumental and sample environmental capabilities the upgrade allows NEAT to maintain itself at the best world class level and provide an outstanding experimental tool for a broad range of scientific applications. The advanced features of the new instrument include an integrated guide-chopper system that delivers neutrons with flexible beam properties: either highly homogeneous beam with low divergence suitable for single crystals studies or “hot-spot” neutron distribution serving best small samples. Substantial increase of the detector angle coverage is achieved by using 416 3He position sensitive detectors. Placed at 3 m from the sample, the detectors cover 20 m2 area and are equipped with modern electronics and DAQ using event recording techniques. The installation of hardware has been completed in June 2016 and on January 23, 2017 NEAT has welcomed its first regular users who took advantage of the high counting rate, broad available range of incoming neutron wavelengths and high flexibility of NEAT. Here we present details of NEAT upgrade, measured instrument characteristics and show first experimental results.
The neutron time-of-flight spectrometer NEAT has a long history of successful applications and is best suited to probe dynamic phenomena directly in the large time domain 10-14 – 10-10 s and on the ...length scale ranging from 0.05 to up to about 5 nm. To address user community needs for more powerful instrumental capabilities, a concept of the full upgrade of NEAT has been proposed. The upgrade started in 2010 after a rigorous internal and external selection process and resulted in 300-fold neutron count rate increase compared to NEAT'1995. Combined with new instrumental and sample environmental capabilities the upgrade allows NEAT to maintain itself at the best world class level and provide an outstanding experimental tool for a broad range of scientific applications. The advanced features of the new instrument include an integrated guide-chopper system that delivers neutrons with flexible beam properties: either highly homogeneous beam with low divergence suitable for single crystals studies or "hot-spot" neutron distribution serving best small samples. Substantial increase of the detector angle coverage is achieved by using 416 3He position sensitive detectors. Placed at 3 m from the sample, the detectors cover 20 m2 area and are equipped with modern electronics and DAQ using event recording techniques. The installation of hardware has been completed in June 2016 and on January 23, 2017 NEAT has welcomed its first regular users who took advantage of the high counting rate, broad available range of incoming neutron wavelengths and high flexibility of NEAT. Here we present details of NEAT upgrade, measured instrument characteristics and show first experimental results.
Bacteria commonly live in spatially structured biofilm assemblages, which are encased by an extracellular matrix. Metabolic activity of the cells inside biofilms causes gradients in local ...environmental conditions, which leads to the emergence of physiologically differentiated subpopulations. Information about the properties and spatial arrangement of such metabolic subpopulations, as well as their interaction strength and interaction length scales are lacking, even for model systems like
colony biofilms grown on agar-solidified media. Here, we use an unbiased approach, based on temporal and spatial transcriptome and metabolome data acquired during
colony biofilm growth, to study the spatial organization of metabolism. We discovered that alanine displays a unique pattern among amino acids and that alanine metabolism is spatially and temporally heterogeneous. At the anoxic base of the colony, where carbon and nitrogen sources are abundant, cells secrete alanine
the transporter AlaE. In contrast, cells utilize alanine as a carbon and nitrogen source in the oxic nutrient-deprived region at the colony mid-height,
the enzymes DadA and DadX. This spatially structured alanine cross-feeding influences cellular viability and growth in the cross-feeding-dependent region, which shapes the overall colony morphology. More generally, our results on this precisely controllable biofilm model system demonstrate a remarkable spatiotemporal complexity of metabolism in biofilms. A better characterization of the spatiotemporal metabolic heterogeneities and dependencies is essential for understanding the physiology, architecture, and function of biofilms.
Microorganisms have evolved specific cell surface molecules that enable discrimination between cells from the same and from a different kind. Here, we investigate the role of Flo11-type cell surface ...adhesins from social yeasts in kin discrimination. We measure the adhesion forces mediated by Flo11A-type domains using single-cell force spectroscopy, quantify Flo11A-based cell aggregation in populations and determine the Flo11A-dependent segregation of competing yeast strains in biofilms. We find that Flo11A domains from diverse yeast species confer remarkably strong adhesion forces by establishing homotypic interactions between single cells, leading to efficient cell aggregation and biofilm formation in homogenous populations. Heterotypic interactions between Flo11A domains from different yeast species or
strains confer weak adhesive forces and lead to efficient strain segregation in heterogenous populations, indicating that in social yeasts Flo11A-mediated cell adhesion is a major mechanism for kin discrimination at species and sub-species levels. These findings, together with our structure and mutation analysis of selected Flo11A domains, provide a rationale of how cell surface receptors have evolved in microorganisms to mediate kin discrimination.
Biofilm formation is critical for the infection cycle of
exopolysaccharides (VPS) and the matrix proteins RbmA, Bap1 and RbmC are required for the development of biofilm architecture. We demonstrate ...that RbmA binds VPS directly and uses a binary structural switch within its first fibronectin type III (FnIII-1) domain to control RbmA structural dynamics and the formation of VPS-dependent higher-order structures. The structural switch in FnIII-1 regulates interactions in trans with the FnIII-2 domain, leading to open (monomeric) or closed (dimeric) interfaces. The ability of RbmA to switch between open and closed states is important for
biofilm formation, as RbmA variants with switches that are locked in either of the two states lead to biofilms with altered architecture and structural integrity.
The toxicity of Loxosceles spider venom has been attributed to a rare enzyme, sphingomyelinase D, which transforms sphingomyelin to ceramide-1-phosphate. The bases of its inflammatory and ...dermonecrotic activity, however, remain unclear. In this work the effects of ceramide-1-phosphate on model membranes were studied both by in situ generation of this lipid using a recombinant sphingomyelinase D from the spider Loxosceles laeta and by pre-mixing it with sphingomyelin and cholesterol. The systems of choice were large unilamellar vesicles for bulk studies (enzyme kinetics, fluorescence spectroscopy and dynamic light scattering) and giant unilamellar vesicles for fluorescence microscopy examination using a variety of fluorescent probes. The influence of membrane lateral structure on the kinetics of enzyme activity and the consequences of enzyme activity on the structure of target membranes containing sphingomyelin were examined. The findings indicate that: 1) ceramide-1-phosphate (particularly lauroyl ceramide-1-phosphate) can be incorporated into sphingomyelin bilayers in a concentration-dependent manner and generates coexistence of liquid disordered/solid ordered domains, 2) the activity of sphingomyelinase D is clearly influenced by the supramolecular organization of its substrate in membranes and, 3) in situ ceramide-1-phosphate generation by enzymatic activity profoundly alters the lateral structure and morphology of the target membranes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Non-alcoholic fatty liver disease ranges from steatosis to non-alcoholic steatohepatitis (NASH), potentially progressing to cirrhosis and hepatocellular carcinoma (HCC). Here, we show that platelet ...number, platelet activation and platelet aggregation are increased in NASH but not in steatosis or insulin resistance. Antiplatelet therapy (APT; aspirin/clopidogrel, ticagrelor) but not nonsteroidal anti-inflammatory drug (NSAID) treatment with sulindac prevented NASH and subsequent HCC development. Intravital microscopy showed that liver colonization by platelets depended primarily on Kupffer cells at early and late stages of NASH, involving hyaluronan-CD44 binding. APT reduced intrahepatic platelet accumulation and the frequency of platelet-immune cell interaction, thereby limiting hepatic immune cell trafficking. Consequently, intrahepatic cytokine and chemokine release, macrovesicular steatosis and liver damage were attenuated. Platelet cargo, platelet adhesion and platelet activation but not platelet aggregation were identified as pivotal for NASH and subsequent hepatocarcinogenesis. In particular, platelet-derived GPIbα proved critical for development of NASH and subsequent HCC, independent of its reported cognate ligands vWF, P-selectin or Mac-1, offering a potential target against NASH.
Background:
An alert algorithm, based on intrathoracic impedance monitoring, has been incorporated into a cardiac resynchronisation device (CRT) to detect pulmonary fluid accumulation, and to audibly ...alert patients to decompensating chronic heart failure (CHF).
Aims:
To evaluate this algorithm, alert events were correlated with changes in NT-proBNP concentration and CHF status.
Methods and results:
In a prospective observational study of 62 patients (89% male, aged 67±1 year), NT-proBNP plasma concentrations, clinical CHF status, and device data were collected at enrolment, during regular follow-up and at device alerts. Over a mean follow-up of 27±2 weeks, pooled data indicated a weak, but significant inverse relationship between relative changes in intrathoracic impedance and NT-proBNP (r=0.3; p<0.001). In 52 device alerts from 35 patients, NT-proBNP increased by 66±19% from 2039±331 pg/ml (p<0.001). The increase in NT-proBNP was higher in alerts with clinical signs of CHF deterioration (n=30, 89±25%;p<0.001) than in alert events without clinical signs (n=22, 25-15%; p=n.s.).
Conclusion:
Intrathoracic impedance based alert events are associated with a significant increase in NT-proBNP concentration. These data indicate that intrathoracic impedance monitoring might facilitate the outpatient management of CHF patients with implanted CRT devices.
Schwarzschild objectives are used in the EUV spectral range because of their large aperture, high mechanical stability and excellent achromaticity. The large aperture results in a small, ...theoretically diffraction limited focus diameter with ideal values of below 200 nm with the current configuration. We employed a zone plate with matched numerical aperture (0.19) to image the focus onto an X-ray CCD camera. Emission from high harmonic generation and a liquid-jet laser-plasma were used as light sources. Images at magnifications of about 150-fold were acquired and focus diameters of 300 nm (FWHM) were observed.
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