3,330 research outputs found
The Clostridioides difficile Cysteine-Rich Exosporium Morphogenetic Protein, CdeC, Exhibits Self-Assembly Properties That Lead to Organized Inclusion Bodies in Escherichia coli
Indexación: Scopus.Clostridioides difficile is an obligately anaerobic, spore-forming, Grampositive pathogenic bacterium that is considered the leading cause of nosocomial diarrhea worldwide. Recent studies have attempted to understand the biology of the outermost layer of C. difficile spores, the exosporium, which is believed to contribute to early interactions with the host. The fundamental role of the cysteine-rich proteins CdeC and CdeM has been described. However, the molecular details behind the mechanism of exosporium assembly are missing. The underlying mechanisms that govern exosporium assembly in C. difficile remain poorly studied, in part due to difficulties in obtaining pure soluble recombinant proteins of the C. difficile exosporium. In this work, we observed that CdeC was able to form organized inclusion bodies (IBs) in Escherichia coli filled with lamella-like structures separated by an interspace of 5 to 15 nm; however, CdeC expression in an E. coli strain with a more oxidative environment led to the loss of the lamella-like organization of CdeC IBs. Additionally, dithiothreitol (DTT) treatment of CdeC inclusion bodies released monomeric soluble forms of CdeC. Deletions in different portions of CdeC did not affect CdeC's ability to aggregate and form oligomers stable under denaturation conditions but affected CdeC's self-assembly properties. Overall, these observations have important implications in further studies elucidating the role of CdeC in the exosporium assembly of C. difficile spores. IMPORTANCE The endospore of Clostridioides difficile is the vehicle for transmission and persistence of the pathogen, and, specifically, the exosporium is the first contact between the host and the spore. The underlying mechanisms that govern exosporium assembly in C. difficile remain understudied, in part due to difficulties in obtaining pure soluble recombinant proteins of the C. difficile exosporium. Understanding the exosporium assembly's molecular bases may be essential to developing new therapies against C. difficile infection.https://journals.asm.org/doi/epub/10.1128/mSphere.01065-2
Primary herpes simplex virus type 1 infection with acute liver failure in solid organ transplantation: Report of three cases and review
Herpes virus infections is not uncommon in solid organ transplantation patients. We report 3 cases with primary Herpes simplex virus type-1 (HSV1) infection with acute liver failure (ALF). This is a rare and potentially fatal entity that could be a donor-derived infection. Although the initial clinical presentation is non-specific, it should be considered as a differential diagnosis in HSV-negative serology patients with liver failure and empirical treatment must be started in combination with a drastic reduction of immunosuppression. A strategy of HSV prophylaxis for pre-transplant HSV seronegative patients must be stablished in order to reduce the risk of clinical disease.© 2022 Published by Elsevier Ltd
Image informatics strategies for deciphering neuronal network connectivity
Brain function relies on an intricate network of highly dynamic neuronal connections that rewires dramatically under the impulse of various external cues and pathological conditions. Among the neuronal structures that show morphologi- cal plasticity are neurites, synapses, dendritic spines and even nuclei. This structural remodelling is directly connected with functional changes such as intercellular com- munication and the associated calcium-bursting behaviour. In vitro cultured neu- ronal networks are valuable models for studying these morpho-functional changes. Owing to the automation and standardisation of both image acquisition and image analysis, it has become possible to extract statistically relevant readout from such networks. Here, we focus on the current state-of-the-art in image informatics that enables quantitative microscopic interrogation of neuronal networks. We describe the major correlates of neuronal connectivity and present workflows for analysing them. Finally, we provide an outlook on the challenges that remain to be addressed, and discuss how imaging algorithms can be extended beyond in vitro imaging studies
Active wetting of epithelial tissues
Development, regeneration and cancer involve drastic transitions in tissue
morphology. In analogy with the behavior of inert fluids, some of these
transitions have been interpreted as wetting transitions. The validity and
scope of this analogy are unclear, however, because the active cellular forces
that drive tissue wetting have been neither measured nor theoretically
accounted for. Here we show that the transition between 2D epithelial
monolayers and 3D spheroidal aggregates can be understood as an active wetting
transition whose physics differs fundamentally from that of passive wetting
phenomena. By combining an active polar fluid model with measurements of
physical forces as a function of tissue size, contractility, cell-cell and
cell-substrate adhesion, and substrate stiffness, we show that the wetting
transition results from the competition between traction forces and contractile
intercellular stresses. This competition defines a new intrinsic lengthscale
that gives rise to a critical size for the wetting transition in tissues, a
striking feature that has no counterpart in classical wetting. Finally, we show
that active shape fluctuations are dynamically amplified during tissue
dewetting. Overall, we conclude that tissue spreading constitutes a prominent
example of active wetting --- a novel physical scenario that may explain
morphological transitions during tissue morphogenesis and tumor progression
Virological and immunological outcome of treatment interruption in HIV-1-infected subjects vaccinated with MVA-B
The most relevant endpoint in therapeutic HIV vaccination is the assessment of time to viral rebound or duration of sustained control of low-level viremia upon cART treatment cessation. Structured treatment interruptions (STI) are however not without risk to the patient and reliable predictors of viral rebound/control after therapeutic HIV-1 vaccination are urgently needed to ensure patient safety and guide therapeutic vaccine development. Here, we integrated immunological and virological parameters together with viral rebound dynamics after STI in a phase I therapeutic vaccine trial of a polyvalent MVA-B vaccine candidate to define predictors of viral control. Clinical parameters, proviral DNA, host HLA genetics and measures of humoral and cellular immunity were evaluated. A sieve effect analysis was conducted comparing pre-treatment viral sequences to breakthrough viruses after STI. Our results show that a reduced proviral HIV-1 DNA at study entry was independently associated with two virological parameters, delayed HIV-1 RNA rebound (p = 0.029) and lower peak viremia after treatment cessation (p = 0.019). Reduced peak viremia was also positively correlated with a decreased number of HLA class I allele associated polymorphisms in Gag sequences in the rebounding virus population (p = 0.012). Our findings suggest that proviral DNA levels and the number of HLA-associated Gag polymorphisms may have an impact on the clinical outcome of STI. Incorporation of these parameters in future therapeutic vaccine trials may guide refined immunogen design and help conduct safer STI approaches
The simulation of molecular clouds formation in the Milky Way
Using 3D hydrodynamic calculations we simulate formation of molecular clouds
in the Galaxy. The simulations take into account molecular hydrogen chemical
kinetics, cooling and heating processes. Comprehensive gravitational potential
accounts for contributions from the stellar bulge, two and four armed spiral
structure, stellar disk, dark halo and takes into account self-gravitation of
the gaseous component. Gas clouds in our model form in the spiral arms due to
shear and wiggle instabilities and turn into molecular clouds after t\simgt
100 Myr. At the times Myr the clouds form hierarchical
structures and agglomerations with the sizes of 100 pc and greater. We analyze
physical properties of the simulated clouds and find that synthetic statistical
distributions like mass spectrum, "mass-size" relation and velocity dispersion
are close to those observed in the Galaxy. The synthetic (galactic
longitude - radial velocity) diagram of the simulated molecular gas
distribution resembles observed one and displays a structure with appearance
similar to Molecular Ring of the Galaxy. Existence of this structure in our
modelling can be explained by superposition of emission from the galactic bar
and the spiral arms at 3-4 kpc.Comment: 10 pages, 8 figure
Holographic flavor on the Higgs branch
In this paper we study the holographic dual, in several spacetime dimensions,
of the Higgs branch of gauge theories with fundamental matter. These theories
contain defects of various codimensionalities, where the matter fields are
located. In the holographic description the matter is added by considering
flavor brane probes in the supergravity backgrounds generated by color branes,
while the Higgs branch is obtained when the color and flavor branes recombine
with each other. We show that, generically, the holographic dual of the Higgs
phase is realized by means of the addition of extra flux on the flavor branes
and by choosing their appropriate embedding in the background geometry. This
suggests a dielectric interpretation in terms of the color branes, whose vacuum
solutions precisely match the F- and D-flatness conditions obtained on the
field theory side. We further compute the meson mass spectra in several cases
and show that when the defect added has codimension greater than zero it
becomes continuous and gapless.Comment: 59 pages, 1 figure;v2: references adde
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