1,786 research outputs found
Antimicrobial susceptibility pattern and multidrug resistance ındex in Pseudomonas aeruginosa among clinical isolates in Denizli, Turkey
Background: Pseudomonas aeruginosa is an important hospital infection agent causing morbidity and mortality with the ability to gain resistance to many antimicrobials. The objective of this study was to determine the sensitivity profiles of nosocomial P. aeruginosa isolates in Denizli, Turkey. Methods: A total 120 P. aeruginosa strains which were isolated from specimens sent to the microbiology laboratory between January 2015 and December 2015 were investigated. Antimicrobial resistance was determined by agar disc diffusion method using Mueller-Hinton agar according to Clinical and Laboratory Standards Institute recommendations. Results: With respect to sensitivity pattern, the most sensitive antimicrobials were Amikacin, colistin, tobramisin, netilmicin and gentamicin and the resistance rates were detected as 97%, 96%, 92%, 90%, 83%, respectively over 120 P. aeruginosa strains. The sensitivity rates for the other antimicrobials were 56% for Piperacilin and 54% for Tazobactam. P. aeruginosa strains 62 (52%) isolates showed multiple antimicrobial resistance to 13 antimicrobials Conclusion: To prevent the spread of the resistant bacteria, it is critically important to have strict antimicrobial policies while surveillance programmes for multidrug resistant organisms and infection control procedures need to be implemented. In the meantime, it is desirable that the antimicrobial susceptibility pattern of bacterial pathogens like P. aeruginosa in specialized clinical units to be continuously monitored and the results readily made available to clinicians so as to minimize the development of resistance. © 2018, National Institute for Medical Research. All rights reserved
Age-related Effects on Social Cognition in Adults with Autism Spectrum Disorder: A Possible Protective Effect on Theory of Mind
Impaired social cognition has been suggested to underlie the social communication difficulties that define autism spectrum disorder (ASD). In typical development, social cognition may deteriorate in older age, but age effects in ASD adults have been little explored. In the present study, we compared groups of younger and older adults with and without ASD (n = 97), who completed a set of social cognition tasks assessing theory of mind (ToM), and self‐report measures of empathy and alexithymia. While typically developing (TD) younger adults outperformed elderly TD and younger ASD participants, younger and older ASD adults did not differ in their ToM performance, and the elderly ASD and TD groups performed equivalently. By contrast, ASD adults reported lower empathy scores and higher levels of alexithymia symptoms compared to TD adults regardless of age. The difference between ASD and TD groups in self‐reported empathy scores was no longer significant when alexithymia was covaried (with the exception of the Perspective Taking subscore). Results suggest a possible age‐protective effect on ToM in the ASD group. In addition, empathy difficulties appear to be associated with alexithymia rather than ASD per se. Possible interpretations are discussed, and future directions for autism aging research are proposed
Soft Listeria: actin-based propulsion of liquid drops
We study the motion of oil drops propelled by actin polymerization in cell
extracts. Drops deform and acquire a pear-like shape under the action of the
elastic stresses exerted by the actin comet. We solve this free boundary
problem and calculate the drop shape taking into account the elasticity of the
actin gel and the variation of the polymerization velocity with normal stress.
The pressure balance on the liquid drop imposes a zero propulsive force if
gradients in surface tension or internal pressure are not taken into account.
Quantitative parameters of actin polymerization are obtained by fitting theory
to experiment.Comment: 5 pages, 4 figure
Formation of filopodia-like bundles in vitro from a dendritic network
We report the development and characterization of an in vitro system for the formation of filopodia-like bundles. Beads coated with actin-related protein 2/3 (Arp2/3)–activating proteins can induce two distinct types of actin organization in cytoplasmic extracts: (1) comet tails or clouds displaying a dendritic array of actin filaments and (2) stars with filament bundles radiating from the bead. Actin filaments in these bundles, like those in filopodia, are long, unbranched, aligned, uniformly polar, and grow at the barbed end. Like filopodia, star bundles are enriched in fascin and lack Arp2/3 complex and capping protein. Transition from dendritic to bundled organization was induced by depletion of capping protein, and add-back of this protein restored the dendritic mode. Depletion experiments demonstrated that star formation is dependent on Arp2/3 complex. This poses the paradox of how Arp2/3 complex can be involved in the formation of both branched (lamellipodia-like) and unbranched (filopodia-like) actin structures. Using purified proteins, we showed that a small number of components are sufficient for the assembly of filopodia-like bundles: Wiskott-Aldrich syndrome protein (WASP)–coated beads, actin, Arp2/3 complex, and fascin. We propose a model for filopodial formation in which actin filaments of a preexisting dendritic network are elongated by inhibition of capping and subsequently cross-linked into bundles by fascin
Differential requirements for actin during yeast and mammalian endocytosis
Key features of clathrin-mediated endocytosis have been conserved across evolution. However, endocytosis in Saccharomyces cerevisiae is completely dependent on a functional actin cytoskeleton, whereas actin appears to be less critical in mammalian cell endocytosis. We reveal that the fundamental requirement for actin in the early stages of yeast endocytosis is to provide a strong framework to support the force generation needed to direct the invaginating plasma membrane into the cell against turgor pressure. By providing osmotic support, pressure differences across the plasma membrane were removed and this reduced the requirement for actin-bundling proteins in normal endocytosis. Conversely, increased turgor pressure in specific yeast mutants correlated with a decreased rate of endocytic patch invagination
Differential Requirements for Clathrin-dependent Endocytosis at Sites of Cell–Substrate Adhesion
Little is known about the influences of cell–substrate attachment in clathrin-mediated endocytosis. We find that cell–substrate adhesion reduces the rate of endocytosis. In addition, we demonstrate that actin assembly is differentially required for efficient endocytosis, with a stronger requirement for actin dynamics at sites of adhesion
The SNX-PX-BAR Family in Macropinocytosis: The Regulation of Macropinosome Formation by SNX-PX-BAR Proteins
Background: Macropinocytosis is an actin-driven endocytic process, whereby membrane ruffles fold back onto the plasma membrane to form large (> 0.2 mu m in diameter) endocytic organelles called macropinosomes. Relative to other endocytic pathways, little is known about the molecular mechanisms involved in macropinocytosis. Recently, members of the Sorting Nexin (SNX) family have been localized to the cell surface and early macropinosomes, and implicated in macropinosome formation. SNX-PX-BAR proteins form a subset of the SNX family and their lipid-binding (PX) and membrane-curvature sensing (BAR) domain architecture further implicates their functional involvement in macropinosome formation
A presynaptic endosomal trafficking pathway controls synaptic growth signaling
Association of Nwk with SNX16 promotes down-regulation of synaptic growth signaling at the interface between early and recycling endosomes
SNX12 Role in Endosome Membrane Transport
In this paper, we investigated the role of sorting nexin 12 (SNX12) in the endocytic pathway. SNX12 is a member of the PX domain-containing sorting nexin family and shares high homology with SNX3, which plays a central role in the formation of intralumenal vesicles within multivesicular endosomes. We found that SNX12 is expressed at very low levels compared to SNX3. SNX12 is primarily associated with early endosomes and this endosomal localization depends on the binding to 3-phosphoinositides. We find that overexpression of SNX12 prevents the detachment (or maturation) of multivesicular endosomes from early endosomes. This in turn inhibits the degradative pathway from early to late endosomes/lysosomes, much like SNX3 overexpression, without affecting endocytosis, recycling and retrograde transport. In addition, while previous studies showed that Hrs knockdown prevents EGF receptor sorting into multivesicular endosomes, we find that overexpression of SNX12 restores the sorting process in an Hrs knockdown background. Altogether, our data show that despite lower expression level, SNX12 shares redundant functions with SNX3 in the biogenesis of multivesicular endosomes
A direct role for SNX9 in the biogenesis of filopodia.
Filopodia are finger-like actin-rich protrusions that extend from the cell surface and are important for cell-cell communication and pathogen internalization. The small size and transient nature of filopodia combined with shared usage of actin regulators within cells confounds attempts to identify filopodial proteins. Here, we used phage display phenotypic screening to isolate antibodies that alter the actin morphology of filopodia-like structures (FLS) in vitro. We found that all of the antibodies that cause shorter FLS interact with SNX9, an actin regulator that binds phosphoinositides during endocytosis and at invadopodia. In cells, we discover SNX9 at specialized filopodia in Xenopus development and that SNX9 is an endogenous component of filopodia that are hijacked by Chlamydia entry. We show the use of antibody technology to identify proteins used in filopodia-like structures, and a role for SNX9 in filopodia
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