503 research outputs found

    Model for coiling and meandering instability of viscous threads

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    A numerical model is presented to describe both the transient and steady-state dynamics of viscous threads falling onto a plane. The steady-state coiling frequency w is calculated as a function of fall height H. In the case of weak gravity, w ~ H^{-1} and w ~ H are obtained for lower and higher fall heights respectively. When the effect of gravity is significant, the relation w ~ H^2 is observed. These results agree with the scaling laws previously predicted. The critical Reynolds number for coil-uncoil transition is discussed. When the gravity is weak, the transition occurs with hysteresis effects. If the plane moves horizontally at a constant speed, a variety of meandering oscillation modes can be observed experimentally. The present model also can describe this phenomenon. The numerically obtained state diagram for the meandering modes qualitatively agrees with the experiment.Comment: 12 pages, 10 figure

    Bouveret's syndrome complicated by distal gallstone ileus after laser lithotropsy using Holmium: YAG laser

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    BACKGROUND: Bouveret's syndrome is an unusual presentation of duodenal obstruction caused by the passage of a large gallstone through a cholecystoduodenal fistula. Endoscopic therapy has been used as first-line treatment, especially in patients with high surgical risk. CASE PRESENTATION: We report a 67-year-old woman who underwent an endoscopic attempt to fragment and retrieve a duodenal stone using a Holmium: Yttrium-Aluminum-Garnet Laser (Ho:YAG) which resulted in small bowel obstruction. The patient successfully underwent enterolithotomy without cholecystectomy or closure of the fistula. CONCLUSION: We conclude that, distal gallstone obstruction, due to migration of partially fragmented stones, can occur as a possible complication of laser lithotripsy treatment of Bouveret's syndrome and might require urgent enterolithotomy

    Temperature dependent BCS equations with continuum coupling

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    The temperature dependent BCS equations are modified in order to include the contribution of the continuum single particle states. The influence of the continuum upon the critical temperature corresponding to the phase transition from a superfluid to a normal state and upon the behaviour of the excitation energy and of the entropy is discussed.Comment: 9 pages, 3 figures, to appear in Phys. Rev.

    When rhythms meet the blues: Circadian interactions with the microbiota-gut-brain axis

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    The microbiota-gut-brain axis encompasses a bidirectional mode of communication between the microorganisms residing in our gut, and our brain function and behavior. The composition of the gut microbiota is subject to diurnal variation and is entrained by host circadian rhythms. In turn, a diverse microbiota is essential for optimal regulation of host circadian pathways. Disruption of the cyclical nature of this microbe-host interaction profoundly influences disease pathology and severity. This review aims to summarize current knowledge on this bidirectional relationship. Indeed, the past few years have revealed promising data regarding the relationship between the microbiota-gut-brain axis and circadian rhythms and how they act in concert to influence disease, but further research needs to be done to examine how they coalesce to modulate severity of, and risk for, certain diseases. Moreover, there is a need for a greater understanding of the molecular mechanisms underlying the close relationship between circadian-microbiome-brain interactions

    The feasibility of canine rabies elimination in Africa: dispelling doubts with data

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    <p><b>Background:</b> Canine rabies causes many thousands of human deaths every year in Africa, and continues to increase throughout much of the continent.</p> <p><b>Methodology/Principal Findings:</b> This paper identifies four common reasons given for the lack of effective canine rabies control in Africa: (a) a low priority given for disease control as a result of lack of awareness of the rabies burden; (b) epidemiological constraints such as uncertainties about the required levels of vaccination coverage and the possibility of sustained cycles of infection in wildlife; (c) operational constraints including accessibility of dogs for vaccination and insufficient knowledge of dog population sizes for planning of vaccination campaigns; and (d) limited resources for implementation of rabies surveillance and control. We address each of these issues in turn, presenting data from field studies and modelling approaches used in Tanzania, including burden of disease evaluations, detailed epidemiological studies, operational data from vaccination campaigns in different demographic and ecological settings, and economic analyses of the cost-effectiveness of dog vaccination for human rabies prevention.</p> <p><b>Conclusions/Significance:</b> We conclude that there are no insurmountable problems to canine rabies control in most of Africa; that elimination of canine rabies is epidemiologically and practically feasible through mass vaccination of domestic dogs; and that domestic dog vaccination provides a cost-effective approach to the prevention and elimination of human rabies deaths.</p&gt

    Specificity and Actions of an Arylaspartate Inhibitor of Glutamate Transport at the Schaffer Collateral-CA1 Pyramidal Cell Synapse

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    In this study we characterized the pharmacological selectivity and physiological actions of a new arylaspartate glutamate transporter blocker, L-threo-ß-benzylaspartate (L-TBA). At concentrations up to 100 µM, L-TBA did not act as an AMPA receptor (AMPAR) or NMDA receptor (NMDAR) agonist or antagonist when applied to outside-out patches from mouse hippocampal CA1 pyramidal neurons. L-TBA had no effect on the amplitude of field excitatory postsynaptic potentials (fEPSPs) recorded at the Schaffer collateral-CA1 pyramidal cell synapse. Excitatory postsynaptic currents (EPSCs) in CA1 pyramidal neurons were unaffected by L-TBA in the presence of physiological extracellular Mg2+ concentrations, but in Mg2+-free solution, EPSCs were significantly prolonged as a consequence of increased NMDAR activity. Although L-TBA exhibited approximately four-fold selectivity for neuronal EAAT3 over glial EAAT1/EAAT2 transporter subtypes expressed in Xenopus oocytes, the L-TBA concentration-dependence of the EPSC charge transfer increase in the absence of Mg2+ was the same in hippocampal slices from EAAT3 +/+ and EAAT3 −/− mice, suggesting that TBA effects were primarily due to block of glial transporters. Consistent with this, L-TBA blocked synaptically evoked transporter currents in CA1 astrocytes with a potency in accord with its block of heterologously expressed glial transporters. Extracellular recording in the presence of physiological Mg2+ revealed that L-TBA prolonged fEPSPs in a frequency-dependent manner by selectively increasing the NMDAR-mediated component of the fEPSP during short bursts of activity. The data indicate that glial glutamate transporters play a dominant role in limiting extrasynaptic transmitter diffusion and binding to NMDARs. Furthermore, NMDAR signaling is primarily limited by voltage-dependent Mg2+ block during low-frequency activity, while the relative contribution of transport increases during short bursts of higher frequency signaling

    Emergent versus delayed lithotripsy for obstructing ureteral stones: a cumulative analysis of comparative studies

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    Objective To analyze the current evidence on the use of ureteroscopy (URS) and extracorporeal shock wave lithotripsy (ESWL) for the management of obstructing ureteral stones in emergent setting. Methods A systematic literature review was performed up to June 2016 using Pubmed and Ovid databases to identify pertinent studies. The PRISMA criteria were followed for article selection. Separate searches were done using a combinations of several search terms: "laser lithotripsy", "ureteroscopy", "extracorporeal shock wave lithotripsy", "ESWL", "rapid", "immediate", "early", "delayed", "late", "ureteral stones", "kidney stones", "renal stones". Only titles related to emergent/rapid/immediate/early (as viably defined in each study) versus delayed/late treatment of ureteral stones with either URS and/or ESWL were considered for screening. Demographics and operative outcomes were compared between emergent and delayed lithotripsy. RevMan review manager software was used to perform data analysis. Results Four studies comparing emergent (n = 526) versus delayed (n = 987) URS and six studies comparing emergent (n = 356) versus delayed (n = 355) SWL were included in the analysis. Emergent URS did not show any significant difference in terms of stone-free rate (91.2 versus 90.9%; OR 1.04; CI 0.71, 1.52; p = 0.84), complication rate (8.7% for emergent versus 11.5% for delayed; OR 0.94; CI 0.65, 1.36; p = 0.74) and need for auxiliary procedures (OR 0.85; CI 0.42, 1.7; p = 0.85) when compared to delayed URS. Emergent ESWL was associated with a higher likelihood of stone free status (OR 2.2; CI 1.55, 3.17; p < 0.001) and a lower likelihood of need for auxiliary maneuvers (OR 0.49; CI 0.33, 0.72; p < 0.001) than the delayed procedure. No differences in complication rates were noticed between the emergent and delayed ESWL (p = 0.37). Conclusions Emergent lithotripsy, either ureteroscopic or extracorporeal, can be offered as an effective and safe treatment for patients with symptomatic ureteral stone. If amenable to ESWL, based on stone and patient characteristics, an emergent approach should be strongly considered. Ureteroscopy in the emergent setting is mostly reserved for distally located stones. The implementation of these therapeutic approaches is likely to be dictated by their availability.info:eu-repo/semantics/publishedVersio

    Relaxin: Review of Biology and Potential Role in Treating Heart Failure

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    Relaxin is a naturally occurring human peptide initially identified as a reproductive hormone. More recently, relaxin has been shown to play a key role in the maternal hemodynamic and renal adjustments that accommodate pregnancy. An understanding of these physiologic effects has led to the evaluation of relaxin as a pharmacologic agent for the treatment of patients with acute heart failure. Preliminary results have been encouraging. In addition, the other known biologic properties of relaxin, including anti-inflammatory effects, extracellular matrix remodeling effects, and angiogenic and anti-ischemic effects, all may play a role in potential benefits of relaxin therapy. Ongoing, large-scale clinical testing will provide additional insights into the potential role of relaxin in the treatment of heart failure

    Effects of danicamtiv, a novel cardiac myosin activator, in heart failure with reduced ejection fraction: experimental data and clinical results from a phase 2a trial

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    Aims: Both left ventricular (LV) and left atrial (LA) dysfunction and remodelling contribute to adverse outcomes in heart failure with reduced ejection fraction (HFrEF). Danicamtiv is a novel, cardiac myosin activator that enhances cardiomyocyte contraction. Methods and results: We studied the effects of danicamtiv on LV and LA function in non‐clinical studies (ex vivo : skinned muscle fibres and myofibrils; in vivo : dogs with heart failure) and in a randomized, double‐blind, single‐ and multiple‐dose phase 2a trial in patients with stable HFrEF (placebo, n = 10; danicamtiv, n = 30; 50–100 mg twice daily for 7 days). Danicamtiv increased ATPase activity and calcium sensitivity in LV and LA myofibrils/muscle fibres. In dogs with heart failure, danicamtiv improved LV stroke volume (+10.6 mL, P &lt; 0.05) and LA emptying fraction (+10.7%, P &lt; 0.05). In patients with HFrEF (mean age 60 years, 25% women, ischaemic heart disease 48%, mean LV ejection fraction 32%), treatment‐emergent adverse events, mostly mild, were reported in 17 patients (57%) receiving danicamtiv and 4 patients (40%) receiving placebo. Danicamtiv (at plasma concentrations ≥2000 ng/mL) increased stroke volume (up to +7.8 mL, P &lt; 0.01), improved global longitudinal (up to −1.0%, P &lt; 0.05) and circumferential strain (up to −3.3%, P &lt; 0.01), decreased LA minimal volume index (up to −2.4 mL/m2, P &lt; 0.01) and increased LA function index (up to 6.1, P &lt; 0.01), when compared with placebo. Conclusions: Danicamtiv was well tolerated and improved LV systolic function in patients with HFrEF. A marked improvement in LA volume and function was also observed in patients with HFrEF, consistent with pre‐clinical findings of direct activation of LA contractility
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