The radiation of a uniformly accelerated charge is beyond the horizon: a simple derivation

We show, by exploring some elementary consequences of the covariance of Maxwell's equations under general coordinate transformations, that, despite inertial observers can indeed detect electromagnetic radiation emitted from a uniformly accelerated charge, comoving observers will see only a static electric field. This simple analysis can help understanding one of the most celebrated paradoxes of last century.Comment: Revtex, 6 pages, 2 figures. v2: Some small corrections. v3: Citation of a earlier paper included. v4: Some stylistic changes. v5: Final version to appear in AJ

Integrated stress response of Escherichia coli to methylglyoxal : transcriptional readthrough from the nemRA operon enhances protection through increased expression of glyoxalase I

© 2013 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.Peer reviewedPublisher PD

Association Between Uric Acid Levels and Obstructive Sleep Apnea Syndrome in a Large Epidemiological Sample

Introduction: Recurrent hypoxia, which is associated with obstructive sleep apnea syndrome (OSAS), leads to an increase in the degradation of adenosine triphosphatase into xanthine, which in turn increases uric acid concentrations.Objective: the current study aimed to determine whether an association exists between OSAS and uric acid levels in the peripheral blood from a representative population of São Paulo (Brazil).Methods: A population-based survey adopting a probabilistic 3-stage cluster sample of São Paulo was used to represent the population according to gender, age, and socioeconomic class. A total of 1,042 volunteers underwent polysomnography recordings for OSAS diagnosis, blood pressure assessment, and biochemical blood analysis, and answered questionnaires.Results: Uric acid levels were correlated with most important risk factors for OSAS, such as AHI, desaturation time and index, minimum oxyhemoglobin saturation (SpO(2)), blood pressure, cholesterol, BMI, triglycerides and arousal, and with OSAS itself. Also, uric acid was increased in OSAS volunteers even after controlling for all confounders. Hyperuricemic volunteers presented lower mean and minimum SpO(2) and increased desaturation index. Importantly, minimum SpO(2) was a significant predictor of uric acid levels, which in turn was considered an independent predictor for OSAS in the binary logistic model. However, a ROC curve analysis for establishing cut-off points for uric acid levels as a biomarker of OSAS revealed moderate sensitivity and specificity.Conclusion: A strong association was found between uric acid levels and OSAS in a representative sample of the population of São Paulo. Although they do not qualify for a biomarker alone, uric acid levels may be involved in OSAS severity and should be considered in sleep apnea management in the future.Associacao Fundo de Incentivo a Pesquisa (AFIP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Dept Psicobiol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Psicobiol, São Paulo, BrazilFAPESP: CEPID 98/14303-3FAPESP: 10/50129-1Web of Scienc

Using Biotic Interaction Networks for Prediction in Biodiversity and Emerging Diseases

Networks offer a powerful tool for understanding and visualizing inter-species interactions within an ecology. Previously considered examples, such as trophic networks, are just representations of experimentally observed direct interactions. However, species interactions are so rich and complex it is not feasible to directly observe more than a small fraction. In this paper, using data mining techniques, we show how potential interactions can be inferred from geographic data, rather than by direct observation. An important application area for such a methodology is that of emerging diseases, where, often, little is known about inter-species interactions, such as between vectors and reservoirs. Here, we show how using geographic data, biotic interaction networks that model statistical dependencies between species distributions can be used to infer and understand inter-species interactions. Furthermore, we show how such networks can be used to build prediction models. For example, for predicting the most important reservoirs of a disease, or the degree of disease risk associated with a geographical area. We illustrate the general methodology by considering an important emerging disease - Leishmaniasis. This data mining approach allows for the use of geographic data to construct inferential biotic interaction networks which can then be used to build prediction models with a wide range of applications in ecology, biodiversity and emerging diseases

Búsqueda de Staphylococcus aureus meticilina resistente aislado de cavidades nasales de estudiantes de Tecnología Médica de la Universidad de Talca

63 p.La resistencia bacteriana a diversos antimicrobianos es un problema que aqueja a los distintos sistemas de salud. Staphylococcus aureus corresponde a un microorganismo Gram positivo causante de diversas infecciones que afectan al hombre. La resistencia de S. aureus a meticilina es un mecanismo presente en cepas que producen significativos brotes de infección intrahospitalaria, pero que en los últimos años se ha difundido a nivel comunitario, pudiendo distinguir cepas asociadas al ambiente hospitalario (SAMR-H) y aquellas que se asocian a la comunidad (SAMR-C). S. aureus puede formar parte de la microbiota en distintos individuos, siendo la portación nasofaríngea la más importante en los seres humanos, en los cuales las probabilidades de desarrollar una infección por este agente son aún mayores que en quienes no lo acarrean, por lo que el objetivo de este estudio correspondió a determinar la portación nasofaríngea de SAMR en estudiantes de Tecnología Médica de la Universidad de Talca. De esta investigación se obtuvieron 147 muestras de estudiantes, utilizando la técnica de difusión en disco con cefoxitina para la pesquisa de SAMR. La portación nasal de S. aureus correspondió a un 21,1%, mientras que la portación de SAMR fue de 10,9%. Las pruebas de susceptibilidad arrojaron un 100% de sensibilidad para ertapenem, linezolid, trimetoprim-sulfametoxazol, moxifloxacino y vancomicina tanto para cepas sensibles como resistentes a la meticilina. Hubo un 100% de resistencia de las cepas de SAMR a penicilina, cloxacilina y ampicilina-sulbactam, un 68,8% de resistencia a cefradina y un 31,2% de resistencia a eritromicina. Con respecto a lincomicina y eritromicina, se presentaron sensibilidades intermedias. Es importante la vigilancia epidemiológica de cepas de SAMRC y la toma de conocimiento de ser un portador sano de este agente, aún más al desarrollarse profesionalmente en el área de la salud, evitando el aumento indiscriminado de estas cepas en la comunidad

Comparison of different surgical approaches for pediatric cataracts: complications and rates of additional surgery during long-term follow-up

OBJECTIVES: To compare long-term postoperative complications of pediatric cataract surgery with primary intraocular lens (IOL) implantation associated with posterior capsulotomy (PC) and anterior vitrectomy (AV) between patients treated with a corneal or pars plicata/pars plana approach. METHODS: Children who underwent cataract surgery with in-the-bag primary IOL implantation were divided into two groups according to PC and AV surgical approach: a corneal approach (group 1) and a pars plicata/pars plana approach (group 2). Only patients with a follow-up duration of more than two years were included. Longterm surgical outcomes were retrospectively reported. RESULTS: The mean follow-up period was 10.00±3.13 years. No cases of glaucoma or retinal detachment were reported. The mean age at surgery was 34.57±22.66 months. Forty-six children were included (27 eyes in group 1 and 29 eyes in group 2). The most frequent postoperative complication was corectopia, followed by visual axis opacification. Both complications occurred more frequently in group 1 (po0.001). After cataract surgery, the rate of additional surgeries in group 1 was 51.9%, while in group 2, the rate was 27.6% (p=0.1132). CONCLUSION: The pars plicata/pars plana approach with PC and vitrectomy with primary in-the-bag IOL implantation for pediatric cataracts is a safe procedure

Characterization of the Adherence of Clostridium difficile Spores: The Integrity of the Outermost Layer Affects Adherence Properties of Spores of the Epidemic Strain R20291 to Components of the Intestinal Mucosa

Indexación: Web of Science.Clostridium difficile is the causative agent of the most frequently reported nosocomial diarrhea worldwide. The high incidence of recurrent infection is the main clinical challenge of C. difficile infections (CBI). Formation of C. difficile spores of the epidemic strain R20291 has been shown to be essential for recurrent infection and transmission of the disease in a mouse model. However, the underlying mechanisms of how these spores persist in the colonic environment remains unclear. In this work, we characterized the adherence properties of epidemic R20291 spores to components of the intestinal mucosa, and we assessed the role of the exosporium integrity in the adherence properties by using cdeC mutant spores with a defective exosporium layer. Our results showed that spores and vegetative cells of the epidemic R20291 strain adhered at high levels to monolayers of Caco-2 cells and mucin. Transmission electron micrographs of Caco-2 cells demonstrated that the hair-like projections on the surface of R20291 spores are in close proximity with the plasma membrane and microvilli of undifferentiated and differentiated monolayers of Caco-2 cells. Competitive-binding assay in differentiated Caco-2 cells suggests that spore-adherence is mediated by specific binding sites. By using spores of a cdeC mutant we demonstrated that the integrity of the exosporium layer determines the affinity of adherence of C. difficile spores to Caco-2 cells and mucin. Binding of fibronectin and vitronectin to the spore surface was concentration-dependent, and depending on the concentration, spore-adherence to Caco-2 cells was enhanced. In the presence of an aberrantly-assembled exosporium (cdeC spores), binding of fibronectin, but not vitronectin, was increased. Notably, independent of the exosporium integrity, only a fraction of the spores had fibronectin and vitronectin molecules binding to their surface. Collectively, these results demonstrate that the integrity of the exosporium layer of strain R20291 contributes to selective spore adherence to components of the intestinal mucosa.http://journal.frontiersin.org/article/10.3389/fcimb.2016.00099/ful