539 research outputs found
Enhanced propagation of motile bacteria on surfaces due to forward scattering
How motile bacteria move near a surface is a problem of fundamental
biophysical interest and is key to the emergence of several phenomena of
biological, ecological and medical relevance, including biofilm formation.
Solid boundaries can strongly influence a cell's propulsion mechanism, thus
leading many flagellated bacteria to describe long circular trajectories stably
entrapped by the surface. Experimental studies on near-surface bacterial
motility have, however, neglected the fact that real environments have typical
microstructures varying on the scale of the cells' motion. Here, we show that
micro-obstacles influence the propagation of peritrichously flagellated
bacteria on a flat surface in a non-monotonic way. Instead of hindering it, an
optimal, relatively low obstacle density can significantly enhance cells'
propagation on surfaces due to individual forward-scattering events. This
finding provides insight on the emerging dynamics of chiral active matter in
complex environments and inspires possible routes to control microbial ecology
in natural habitats
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Proposed Regulation of Gene Expression by Glucose in Rodent Heart
Background: During pressure overload-induced hypertrophy, unloading-induced atrophy, and diabetes mellitus, the heart induces ‘fetal’ genes (e.g. myosin heavy chain β; mhcβ). Hypothesis: We propose that altered glucose homeostasis within the cardiomyocyte acts as a central mechanism for the regulation of gene expression in response to environmental stresses. The evidence is as follows. Methods and Results: Forced glucose uptake both ex vivo and in vivo results in mhc isoform switching. Restricting dietary glucose prevents mhc isoform switching in hearts of both GLUT1-Tg mice and rats subjected to pressure overload-induced hypertrophy. Thus, glucose availability correlates with mhc isoform switching under all conditions investigated. A potential mechanism by which glucose affects gene expression is through O-linked glycosylation of specific transcription factors. Glutamine:fructose-6-phosphate amidotransferase (GFAT) catalyzes the flux generating step in UDP-N-acetylglucosamine biosynthesis, the rate determining metabolite in protein glycosylation. Ascending aortic constriction increased intracellular levels of UDP-N-acetylglucosamine, and the expression of gfat2, but not gfat1, in the rat heart. Conclusions: Collectively, the results strongly suggest glucose-regulated gene expression in the heart, and the involvement of glucose metabolites in isoform switching of sarcomeric proteins characteristic for the fetal gene program
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Imbalance in Coagulation/Fibrinolysis Inhibitors Resulting in Extravascular Thrombin Generation in Gliomas of Varying Levels of Malignancy.
Neoplastic processes are integrally related to disturbances in the mechanisms regulating hemostatic processes. Brain tumors, including gliomas, are neoplasms associated with a significantly increased risk of thromboembolic complications, affecting 20-30% of patients. As gliomas proliferate, they cause damage to the brain tissue and vascular structures, which leads to the release of procoagulant factors into the systemic circulation, and hence systemic activation of the blood coagulation system. Hypercoagulability in cancer patients may be, at least in part, a result of the inadequate activity of coagulation inhibitors. The aim of the study was to evaluate the expression of the inhibitors of the coagulation and fibrinolysis systems (tissue factor pathway inhibitor, TFPI; tissue factor pathway inhibitor-2 TFPI-2; protein C, PC; protein S, PS, thrombomodulin, TM; plasminogen activators inhibitor, PAI-1) in gliomas of varying degrees of malignancy. Immunohistochemical studies were performed on 40 gliomas, namely on 13 lower-grade (G2) gliomas (8 astrocytomas, 5 oligodendrogliomas) and 27 high-grade gliomas (G3-12 anaplastic astrocytomas, 4 anaplastic oligodendrogliomas; G4-11 glioblastomas). A strong expression of TFPI-2, PS, TM, PAI-1 was observed in lower-grade gliomas, while an intensive color immunohistochemical (IHC) reaction for the presence of TFPI antigens was detected in higher-grade gliomas. The presence of PC antigens was found in all gliomas. Prothrombin fragment 1+2 was observed in lower- and higher-grade gliomas reflecting local activation of blood coagulation. Differences in the expression of coagulation/fibrinolysis inhibitors in the tissues of gliomas with varying degrees of malignancy may be indicative of their altered role in gliomas, going beyond that of their functions in the hemostatic system
MLP: a MATLAB toolbox for rapid and reliable auditory threshold estimation
In this paper, we present MLP, a MATLAB toolbox enabling auditory
thresholds estimation via the adaptive Maximum Likelihood procedure proposed
by David Green (1990, 1993). This adaptive procedure is particularly appealing for
those psychologists that need to estimate thresholds with a good degree of accuracy
and in a short time. Together with a description of the toolbox, the current text
provides an introduction to the threshold estimation theory and a theoretical
explanation of the maximum likelihood adaptive procedure. MLP comes with a
graphical interface and it is provided with several built-in, classic psychoacoustics
experiments ready to use at a mouse click
A composite double-/single-stranded RNA-binding region in protein Prp3 supports tri-snRNP stability and splicing
Prp3 is an essential U4/U6 di-snRNP-associated protein whose functions and
molecular mechanisms in pre-mRNA splicing are presently poorly understood. We
show by structural and biochemical analyses that Prp3 contains a bipartite
U4/U6 di-snRNA-binding region comprising an expanded ferredoxin-like fold,
which recognizes a 3′-overhang of U6 snRNA, and a preceding peptide, which
binds U4/U6 stem II. Phylogenetic analyses revealed that the single-stranded
RNA-binding domain is exclusively found in Prp3 orthologs, thus qualifying as
a spliceosome-specific RNA interaction module. The composite double-stranded
/single-stranded RNA-binding region assembles cooperatively with Snu13 and
Prp31 on U4/U6 di-snRNAs and inhibits Brr2-mediated U4/U6 di-snRNA unwinding
in vitro. RNP-disrupting mutations in Prp3 lead to U4/U6•U5 tri-snRNP assembly
and splicing defects in vivo. Our results reveal how Prp3 acts as an important
bridge between U4/U6 and U5 in the tri-snRNP and comparison with a Prp24-U6
snRNA recycling complex suggests how Prp3 may be involved in U4/U6 reassembly
after splicing
Low Hydrophobic Mismatch Scores Calculated for HLA-A/B/DR/DQ Loci Improve Kidney Allograft Survival
We evaluated the impact of human leukocyte antigen (HLA) disparity (immunogenicity; IM) on long-term kidney allograft survival. The IM was quantified based on physicochemical properties of the polymorphic linear donor/recipient HLA amino acids (the Cambridge algorithm) as a hydrophobic, electrostatic, amino acid mismatch scores (HMS\AMS\EMS) or eplet mismatch (EpMM) load. High-resolution HLA-A/B/DRB1/DQB1 types were imputed to calculate HMS for primary/re-transplant recipients of deceased donor transplants. The multiple Cox regression showed the association of HMS with graft survival and other confounders. The HMS integer 0-10 scale showed the most survival benefit between HMS 0 and 3. The Kaplan-Meier analysis showed that: the HMS=0 group had 18.1-year median graft survival, a 5-year benefit over HMS\u3e0 group; HMS ≤ 3.0 had 16.7-year graft survival, a 3.8-year better than HMS\u3e3.0 group; and, HMS ≤ 7.8 had 14.3-year grafts survival, a 1.8-year improvement over HMS\u3e7.8 group. Stratification based on EMS, AMS or EpMM produced similar results. Additionally, the importance of HLA-DR with/without -DQ IM for graft survival was shown. In our simulation of 1,000 random donor/recipient pairs, 75% with HMS\u3e3.0 were re-matched into HMS ≤ 3.0 and the remaining 25% into HMS≥7.8: after re-matching, the 13.5 years graft survival would increase to 16.3 years. This approach matches donors to recipients with low/medium IM donors thus preventing transplants with high IM donors
Home parenteral nutrition with an omega-3-fatty-acid-enriched MCT/LCT lipid emulsion in patients with chronic intestinal failure (the HOME study):study protocol for a randomized, controlled, multicenter, international clinical trial
BACKGROUND: Home parenteral nutrition (HPN) is a life-preserving therapy for patients with chronic intestinal failure (CIF) indicated for patients who cannot achieve their nutritional requirements by enteral intake. Intravenously administered lipid emulsions (ILEs) are an essential component of HPN, providing energy and essential fatty acids, but can become a risk factor for intestinal-failure-associated liver disease (IFALD). In HPN patients, major effort is taken in the prevention of IFALD. Novel ILEs containing a proportion of omega-3 polyunsaturated fatty acids (n-3 PUFA) could be of benefit, but the data on the use of n-3 PUFA in HPN patients are still limited. METHODS/DESIGN: The HOME study is a prospective, randomized, controlled, double-blind, multicenter, international clinical trial conducted in European hospitals that treat HPN patients. A total of 160 patients (80 per group) will be randomly assigned to receive the n-3 PUFA-enriched medium/long-chain triglyceride (MCT/LCT) ILE (Lipidem/Lipoplus® 200 mg/ml, B. Braun Melsungen AG) or the MCT/LCT ILE (Lipofundin® MCT/LCT/Medialipide® 20%, B. Braun Melsungen AG) for a projected period of 8 weeks. The primary endpoint is the combined change of liver function parameters (total bilirubin, aspartate transaminase and alanine transaminase) from baseline to final visit. Secondary objectives are the further evaluation of the safety and tolerability as well as the efficacy of the ILEs. DISCUSSION: Currently, there are only very few randomized controlled trials (RCTs) investigating the use of ILEs in HPN, and there are very few data at all on the use of n-3 PUFAs. The working hypothesis is that n-3 PUFA-enriched ILE is safe and well-tolerated especially with regard to liver function in patients requiring HPN. The expected outcome is to provide reliable data to support this thesis thanks to a considerable number of CIF patients, consequently to broaden the present evidence on the use of ILEs in HPN. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT03282955. Registered on 14 September 2017
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Spectroscopic investigation of the formation of hypochlorite, radiolysis by-product in 5 M NaCI featuring high-energy proton beam line experiments.
Because geological salt formations are considered possible sites for radioactive waste disposal, plausible inundation scenario of salt repository will allow chloride brines to be formed, which consequently will be exposed to radiation from the waste. Key radioelements in Intermediate Level Waste (ILW),H igh Level Waste (HLW) or TRU waste have been found to be plutonium, americium, neptunium, uranium, and technetium. Therefore, the effect of radiolysis on high-saline brine under simulated repository conditions are of particular importance because it results in oxidizing chlorine-containing species, such as hypochlorite (OC1-), and hypochlorous acid (HOCI), which may oxidize actinide species to higher oxidation states. Meaningful predictions of long-term redox conditions in a nuclear repository strongly rely on estimations of G-values of the irradiation-induced formation of the oxidizers OC1- and HOCI. G-values not only depend on the total absorbed doses over the relevant timeframe, but also on the kind of irradiation involved. In fact, the G-values of hypochlorite produced by {alpha}-, {beta}-, {gamma}-, or neutron irradiation differ by an order of magnitude, depending on different LET cross-sections. To overcome the serious constrains and obstacles of conventional radiochemical work within GBq/L activity levels, we are going to simulate {alpha}-irradiation of chloride brines by the adaptation of beam-line experiments. Our long-term goal is to demonstrate how the main oxidizing chloride species such as hypochlorite caused by radiolysis may affect the overall behavior of actinides under salt repository conditions. This paper describes our first steps towards the production, the identification and the determination of these oxidizing species by beam line experiments
Endogenous Renal Adiponectin Drives Gluconeogenesis Through Enhancing Pyruvate and Fatty Acid Utilization
Adiponectin is a secretory protein, primarily produced in adipocytes. However, low but detectable expression of adiponectin can be observed in cell types beyond adipocytes, particularly in kidney tubular cells, but its local renal role is unknown. We assessed the impact of renal adiponectin by utilizing male inducible kidney tubular cell-specific adiponectin overexpression or knockout mice. Kidney-specific adiponectin overexpression induces a doubling of phosphoenolpyruvate carboxylase expression and enhanced pyruvate-mediated glucose production, tricarboxylic acid cycle intermediates and an upregulation of fatty acid oxidation (FAO). Inhibition of FAO reduces the adiponectin-induced enhancement of glucose production, highlighting the role of FAO in the induction of renal gluconeogenesis. In contrast, mice lacking adiponectin in the kidney exhibit enhanced glucose tolerance, lower utilization and greater accumulation of lipid species. Hence, renal adiponectin is an inducer of gluconeogenesis by driving enhanced local FAO and further underlines the important systemic contribution of renal gluconeogenesis
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