629 research outputs found

    The Spectral Zeta Function for Laplace Operators on Warped Product Manifolds of the type I×fNI\times_{f} N

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    In this work we study the spectral zeta function associated with the Laplace operator acting on scalar functions defined on a warped product of manifolds of the type I×fNI\times_{f} N where II is an interval of the real line and NN is a compact, dd-dimensional Riemannian manifold either with or without boundary. Starting from an integral representation of the spectral zeta function, we find its analytic continuation by exploiting the WKB asymptotic expansion of the eigenfunctions of the Laplace operator on MM for which a detailed analysis is presented. We apply the obtained results to the explicit computation of the zeta regularized functional determinant and the coefficients of the heat kernel asymptotic expansion.Comment: 29 pages, LaTe

    Relationship between blood remifentanil concentration and stress hormone levels during pneumoperitoneum in patients undergoing laparoscopic cholecystectomy

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    The effect of remifentanil on stress response to surgery is unclear. However, there are not clinical studies investigating the relationship between blood remifentanil concentrations and stress hormones. Therefore, the aim of the present study was to assess the association between blood remifentanil concentrations measured after pneumoperitoneum and cortisol (CORT) or prolactin (PRL) ratio (intraoperative/preoperative value), in patients undergoing laparoscopic cholecystectom

    Scalar Casimir effect between two concentric D-dimensional spheres

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    The Casimir energy for a massless scalar field between the closely spaced two concentric D-dimensional (for D>3) spheres is calculated by using the mode summation with contour integration in the complex plane of eigenfrequencies and the generalized Abel-Plana formula for evenly spaced eigenfrequency at large argument. The sign of the Casimir energy between closely spaced two concentric D-dimensional spheres for a massless scalar field satisfying the Dirichlet boundary conditions is strictly negative. The Casimir energy between D-1 dimensional surfaces close to each other is regarded as interesting both by itself and as the key to describing of stability of the attractive Casimir force. PACS number(s): 03.70.+k, 11.10.Kk, 11.10.Gh, 03.65.GeComment: 14 pages. arXiv admin note: substantial text overlap with arXiv:1207.418

    Acute Disseminated Encephalomyelitis followed by Optic Neuritis: A Rare Syndrome of Uncertain Treatment and Prognosis

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    Aim Acute Disseminated Encephalomyelitis followed by optic neuritis (ADEM-ON), first described in 2013, is a rare demyelinating syndrome, typical of the pediatric age. We conducted a mini review of the existing literature, focusing on clinical, laboratory, radiological, therapeutic, and prognostic aspects in order to improve the identification of new cases. Methods We searched PubMed and Cochrane Library for studies on ADEM-ON between 2013 and 2018. Results Examination of the reported cases (three case reports and eight observational studies) established the following features. Time between ADEM and ON is highly variable. Almost all patients show antimyelin oligodendrocyte glycoprotein antibody (MOG-abs) seropositivity. High-dose intravenous steroid and plasmapheresis efficacy is reported for the acute phase; oral prednisone and other maintenance drugs may be useful in avoiding relapses. The clinical history may lead to a complete recovery but also to residual deficits. Conclusion MOG-abs detection strongly supports ADEM-ON diagnosis, confirming this entity as part of MOG-abs spectrum disorder. Owing to the very small number of cases so far reported, predicting clinical evolution is very difficult

    Fatal injection of ranitidine: a case report

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    ABSTRACT: INTRODUCTION: Ranitidine hydrochloride (Zantac(R)), a histamine-2-receptor antagonist, is a widely used medication with an excellent safety record. Anaphylactic reaction to ranitidine is an extremely rare event and a related death has never been described in the literature. CASE PRESENTATION: We present the clinical history, histological and toxicological data of a 51-year-old man with negative anamnesis for allergic events, who died suddenly after the intravenous administration of one phial of Zantac(R) 50 mg prescribed as a routine post-surgical prophylaxis for stress ulcer. CONCLUSION: Although the incidence of anaphylactic reactions related to ranitidine is low, caution needs to be exercised on administration of this drug. In addition, further study is needed to define strategies for the prevention of adverse drug reactions in hospitalized patients

    Evolution of anterior Hox regulatory elements among chordates

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    <p>Abstract</p> <p>Background</p> <p>The <it>Hox </it>family of transcription factors has a fundamental role in segmentation pathways and axial patterning of embryonic development and their clustered organization is linked with the regulatory mechanisms governing their coordinated expression along embryonic axes. Among chordates, of particular interest are the <it>Hox </it>paralogous genes in groups 1-4 since their expression is coupled to the control of regional identity in the anterior nervous system, where the highest structural diversity is observed.</p> <p>Results</p> <p>To investigate the degree of conservation in <it>cis</it>-regulatory components that form the basis of <it>Hox </it>expression in the anterior nervous system, we have used assays for transcriptional activity in ascidians and vertebrates to compare and contrast regulatory potential. We identified four regulatory sequences located near the <it>CiHox1, CiHox2 </it>and <it>CiHox4 </it>genes of the ascidian <it>Ciona intestinalis </it>which direct neural specific domains of expression. Using functional assays in <it>Ciona </it>and vertebrate embryos in combination with sequence analyses of enhancer fragments located in similar positions adjacent to <it>Hox </it>paralogy group genes, we compared the activity of these four <it>Ciona cis</it>-elements with a series of neural specific enhancers from the amphioxus <it>Hox1-3 </it>genes and from mouse <it>Hox </it>paralogous groups 1-4.</p> <p>Conclusions</p> <p>This analysis revealed that Kreisler and Krox20 dependent enhancers critical in segmental regulation of the hindbrain appear to be specific for the vertebrate lineage. In contrast, neural enhancers that function as <it>Hox </it>response elements through the action of Hox/Pbx binding motifs have been conserved during chordate evolution. The functional assays reveal that these <it>Hox </it>response <it>cis</it>-elements are recognized by the regulatory components of different and extant species. Together, our results indicate that during chordate evolution, <it>cis</it>-elements dependent upon Hox/Pbx regulatory complexes, are responsible for key aspects of segmental <it>Hox </it>expression in neural tissue and appeared with urochordates after cephalochordate divergence.</p

    uPAR controls vasculogenic mimicry ability expressed by drug-resistant melanoma cells.

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    Malignant melanoma is a highly aggressive skin cancer characterized by an elevated grade of tumor cell plasticity. Such plasticity allows adaptation of melanoma cells to different hostile conditions and guarantees tumor survival and disease progression, including aggressive features such as drug resistance. Indeed, almost 50% of melanoma rapidly develop resistance to the BRAF(V600E) inhibitor vemurafenib, with fast tumor dissemination, a devastating consequence for patients’ outcomes. Vasculogenic mimicry (VM), the ability of cancer cells to organize themselves in perfused vascular-like channels, might sustain tumor spread by providing vemurafenib-resistant cancer cells with supplementary ways to enter into circulation and disseminate. Thus, this research aims to determine if vemurafenib resistance goes with the acquisition of VM ability by aggressive melanoma cells, and identify a driving molecule for both vemurafenib resistance and VM. We used two independent experimental models of drug-resistant melanoma cells, the first one represented by a chronic adaptation of melanoma cells to extracellular acidosis, known to drive a particularly aggressive and vemurafenib-resistant phenotype, the second one generated with chronic vemurafenib exposure. By performing in vitro tube formation assay and evaluating the expression levels of the VM markers EphA2 and VE-cadherin by Western blotting and flow cytometer analyses, we demonstrated that vemurafenib-resistant cells obtained by both models are characterized by an increased ability to perform VM. Moreover, by exploiting the CRISPR-Cas9 technique and using the urokinase plasminogen activator receptor (uPAR) inhibitor M25, we identified uPAR as a driver of VM expressed by vemurafenib-resistant melanoma cells. Thus, uPAR targeting may be successfully leveraged as a new complementary therapy to inhibit VM in drug-resistant melanoma patients, to counteract the rapid progression and dissemination of the disease

    New Developments in the Spectral Asymptotics of Quantum Gravity

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    A vanishing one-loop wave function of the Universe in the limit of small three-geometry is found, on imposing diffeomorphism-invariant boundary conditions on the Euclidean 4-ball in the de Donder gauge. This result suggests a quantum avoidance of the cosmological singularity driven by full diffeomorphism invariance of the boundary-value problem for one-loop quantum theory. All of this is made possible by a peculiar spectral cancellation on the Euclidean 4-ball, here derived and discussed.Comment: 7 pages, latex file. Paper prepared for the Conference "QFEXT05: Quantum Field Theory Under the Influence of External Conditions", Barcelona, September 5 - September 9, 2005. In the final version, the presentation has been further improved, and yet other References have been adde
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