1,009 research outputs found

    Pharmacological Or Genetic Targeting Of Transient Receptor Potential (TRP) Channels Can Disrupt The Planarian Escape Response

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    In response to noxious stimuli, planarians cease their typical ciliary gliding and exhibit an oscillatory type of locomotion called scrunching. We have previously characterized the biomechanics of scrunching and shown that it is induced by specific stimuli, such as amputation, noxious heat, and extreme pH. Because these specific inducers are known to activate Transient Receptor Potential (TRP) channels in other systems, we hypothesized that TRP channels control scrunching. We found that chemicals known to activate TRPA1 (allyl isothiocyanate (AITC) and hydrogen peroxide) and TRPV (capsaicin and anandamide) in other systems induce scrunching in the planarian species Dugesia japonica and, except for anandamide, in Schmidtea mediterranea. To confirm that these responses were specific to either TRPA1 or TRPV, respectively, we tried to block scrunching using selective TRPA1 or TRPV antagonists and RNA interference (RNAi) mediated knockdown. Unexpectedly, co-treatment with a mammalian TRPA1 antagonist, HC-030031, enhanced AITC-induced scrunching by decreasing the latency time, suggesting an agonistic relationship in planarians. We further confirmed that TRPA1 in both planarian species is necessary for AITC-induced scrunching using RNAi. Conversely, while co-treatment of a mammalian TRPV antagonist, SB-366791, also enhanced capsaicin-induced reactions in D. japonica, combined knockdown of two previously identified D. japonica TRPV genes (DjTRPVa and DjTRPVb) did not inhibit capsaicin-induced scrunching. RNAi of DjTRPVa/DjTRPVb attenuated scrunching induced by the endocannabinoid and TRPV agonist, anandamide. Overall, our results show that although scrunching induction can involve different initial pathways for sensing stimuli, this behavior’s signature dynamical features are independent of the inducer, implying that scrunching is a stereotypical planarian escape behavior in response to various noxious stimuli that converge on a single downstream pathway. Understanding which aspects of nociception are conserved or not across different organisms can provide insight into the underlying regulatory mechanisms to better understand pain sensation

    Characterization of Streptomyces strain SLO-105 isolated from Lake Oubeira sediments in North-East of Algeria

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    A microbial strain, SLO-105, isolated from Lake Oubeira sediment was screened for its antimicrobial activity against pathogenic bacteria and fungi. The strain showed broad-spectrum antibacterial activity against Gram-positive bacteria Staphylococcus aureus MRSA, Bacillus subtilus, Micrococcus leutus,Streptococcus fecalis and fungi Aspergillus niger and Rodotorulla mucilaginosa. However, no activity of the strain was observed against Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa as well as on fungi Candida albicans. Analysis of 16S rDNA sequence and themorphological and physiological characteristics of the strain suggested that the isolate belonged to Streptomyces genus

    An Inverse Method for Policy-Iteration Based Algorithms

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    We present an extension of two policy-iteration based algorithms on weighted graphs (viz., Markov Decision Problems and Max-Plus Algebras). This extension allows us to solve the following inverse problem: considering the weights of the graph to be unknown constants or parameters, we suppose that a reference instantiation of those weights is given, and we aim at computing a constraint on the parameters under which an optimal policy for the reference instantiation is still optimal. The original algorithm is thus guaranteed to behave well around the reference instantiation, which provides us with some criteria of robustness. We present an application of both methods to simple examples. A prototype implementation has been done

    'Do not attempt resuscitation' and 'cardiopulmonary resuscitation' in an inpatient setting : factors influencing physicians' decisions in Switzerland

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    To determine the prevalence of cardiopulmonary resuscitation (CPR) and do-not-attempt-resuscitation (DNAR) orders, to define factors associated with CPR/DNAR orders and to explore how physicians make and document these decisions. We prospectively reviewed CPR/DNAR forms of 1,446 patients admitted to the General Internal Medicine Department of the Geneva University Hospitals, a tertiary-care teaching hospital in Switzerland. We additionally administered a face-to-face survey to residents in charge of 206 patients including DNAR and CPR orders, with or without patient inclusion.; 21.2% of the patients had a DNAR order, 61.7% a CPR order and 17.1% had neither. The two main factors associated with DNAR orders were a worse prognosis and/or a worse quality of life. Others factors were an older age, cancer and psychiatric diagnoses, and the absence of decision-making capacity. Residents gave four major justifications for DNAR orders: important comorbid conditions (34%), the patients' or their family's resuscitation preferences (18%), the patients' age (14.2%), and the absence of decision-making capacity (8%). Residents who wrote DNAR orders were more experienced. In many of the DNAR or CPR forms (19.8 and 16%, respectively), the order was written using a variety of formulations. For 24% of the residents, the distinction between the resuscitation order and the care objective was not clear. 38% of the residents found the resuscitation form useful.; Patients' prognosis and quality of life were the two main independent factors associated with CPR/DNAR orders. However, in the majority of cases, residents evaluated prognosis only intuitively, and quality of life without involving the patients. The distinction between CPR/DNAR orders and the care objectives was not always clear. Specific training regarding CPR/DNAR orders is necessary to improve the CPR/DNAR decision process used by physicians

    Improving Strategies via SMT Solving

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    We consider the problem of computing numerical invariants of programs by abstract interpretation. Our method eschews two traditional sources of imprecision: (i) the use of widening operators for enforcing convergence within a finite number of iterations (ii) the use of merge operations (often, convex hulls) at the merge points of the control flow graph. It instead computes the least inductive invariant expressible in the domain at a restricted set of program points, and analyzes the rest of the code en bloc. We emphasize that we compute this inductive invariant precisely. For that we extend the strategy improvement algorithm of [Gawlitza and Seidl, 2007]. If we applied their method directly, we would have to solve an exponentially sized system of abstract semantic equations, resulting in memory exhaustion. Instead, we keep the system implicit and discover strategy improvements using SAT modulo real linear arithmetic (SMT). For evaluating strategies we use linear programming. Our algorithm has low polynomial space complexity and performs for contrived examples in the worst case exponentially many strategy improvement steps; this is unsurprising, since we show that the associated abstract reachability problem is Pi-p-2-complete
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