First Report and Comparative Genomics Analysis of a blaOXA-244-Harboring Escherichia coli Isolate Recovered in the American Continent

The carbapenemase OXA-244 is a derivate of OXA-48, and its detection is very difficult in laboratories. Here, we report the identification and genomic analysis of an Escherichia coli isolate (28Eco12) harboring the blaOXA-244 gene identified in Colombia, South America. The 28Eco12 isolate was identified during a retrospective study, and it was recovered from a patient treated in Colombia. The complete nucleotide sequence was established using the PacBio platform. A comparative genomics analysis with other blaOXA-244–harboring Escherichia coli strains was performed. The 28Eco12 isolate belonged to sequence type (ST) 38, and its genome was composed of two molecules, a chromosome of 5,343,367 bp and a plasmid of 92,027 bp, which belonged to the incompatibility group IncY and did not harbor resistance genes. The blaOXA-244 gene was chromosomally encoded and mobilized by an ISR1-related Tn6237 composite transposon. Notably, this transposon was inserted and located within a new genomic island. To our knowledge, this is the first report of a blaOXA-244–harboring Escherichia coli isolate in America. Our results suggest that the introduction of the OXA-244-producing E. coli isolate was through clonal expansion of the ST38 pandemic clone. Other isolates producing OXA-244 could be circulating silently in America.</jats:p

Nonthermal Emission from Star-Forming Galaxies

The detections of high-energy gamma-ray emission from the nearby starburst galaxies M82 & NGC253, and other local group galaxies, broaden our knowledge of star-driven nonthermal processes and phenomena in non-AGN star-forming galaxies. We review basic aspects of the related processes and their modeling in starburst galaxies. Since these processes involve both energetic electrons and protons accelerated by SN shocks, their respective radiative yields can be used to explore the SN-particle-radiation connection. Specifically, the relation between SN activity, energetic particles, and their radiative yields, is assessed through respective measures of the particle energy density in several star-forming galaxies. The deduced energy densities range from O(0.1) eV/cm^3 in very quiet environments to O(100) eV/cm^3 in regions with very high star-formation rates.Comment: 17 pages, 5 figures, to be published in Astrophysics and Space Science Proceeding

Multifrequency Strategies for the Identification of Gamma-Ray Sources

More than half the sources in the Third EGRET (3EG) catalog have no firmly established counterparts at other wavelengths and are unidentified. Some of these unidentified sources have remained a mystery since the first surveys of the gamma-ray sky with the COS-B satellite. The unidentified sources generally have large error circles, and finding counterparts has often been a challenging job. A multiwavelength approach, using X-ray, optical, and radio data, is often needed to understand the nature of these sources. This chapter reviews the technique of identification of EGRET sources using multiwavelength studies of the gamma-ray fields.Comment: 35 pages, 22 figures. Chapter prepared for the book "Cosmic Gamma-ray Sources", edited by K.S. Cheng and G.E. Romero, to be published by Kluwer Academic Press, 2004. For complete article and higher resolution figures, go to: http://www.astro.columbia.edu/~muk/mukherjee_multiwave.pd

Orodispersible tablets: therapeutic and technological advantages of development

Los comprimidos bucodispersables se definen como comprimidos no recubiertos destinados a ser colocados en la boca, donde se dispersan rápidamente antes de ser tragados. Estas formulaciones son conocidas por las siglas FDDT´s (Fast Dissolving Disintegrating Tablets). Son útiles para la administración a pacientes con dificultades en la deglución, presentan una elevada aceptación por parte del paciente, mejoran de la biodisponibilidad del principio activo y suponen una nueva alternativa para la industria farmacéutica. Dentro de sus inconvenientes destacan el poco conocimiento por parte del paciente, la baja resistencia mecánica, su mayor susceptibilidad a la degradación por temperatura y humedad; la falta, a veces, de bioequivalencia con las formulaciones convencionales, y la dificultad de obtener liberaciones prolongadas o retardadas del principio activo.A nivel tecnológico, existen varios procesos que se pueden aplicar en su elaboración. Con los métodos clásicos de elaboración de comprimidos, mediante la correcta selección de los excipientes y de las variables de la etapa de compresión se obtienen unos comprimidos en los que existe un equilibrio entre dureza y disgregación. Han surgido una serie de tecnologías novedosas: Flashtab, Wowtab, Orasolv y Durasolv. Otra opción es el empleo de técnicas de liofilización, aunque presenta como desventaja su alto coste. Algunas tecnologías especiales patentadas como son Lyoc, QuickSolv y Zydis. Por último, estos comprimidos se pueden elaborar por el método de los polímeros entrecruzados, también conocido como FlashDose y se basa en la formación de una matriz de hilos de azúcares entrelazados.The orally disintegrating tablets are defined as non-coated tablets intended to be placed in the mouth where they disperse rapidly before being swallowed. These formulations are known by the acronym FDDT's (Fast Dissolving Disintegrating Tablets). They are useful for administration to patients with swallowing difficulties, have a high acceptance by the patient, improve bioavailability of the active ingredient and represent a new alternative for the pharmaceutical industry. Among its disadvantages include limited knowledge by the patient, low mechanical strength, increased susceptibility to degradation by temperature and humidity; lack sometimes bioequivalence with conventional formulations, and the difficulty of obtaining prolonged release or delayed active ingredient. At the technological level, there are several processes that can be applied in their preparation. With classical methods of tabletting, by proper selection of excipients and the variables of the compression stage a tablet in which there is a balance between hardness and disintegration are obtained. Flashtab, Wowtab, Orasolv and Durasolv: They have a number of new technologies emerged. Another option is the use of freeze drying techniques, but has the disadvantage of its high cost. Some special patented technologies such as Lyoc, QuickSolv and Zydis. Finally, these tablets may be made by the method of Crosslinked polymers, also known as FlashDose and is based on the formation of a matrix of interwoven threads sugars

Non-minimal Quintessence: Dynamics and coincidence problem

Brans--Dicke scalar--tensor theory provides a conformally coupling of the scalar field with gravity in Einstein's frame. This model is equivalent to an interacting quintessence in which dark matter is coupled to dark energy. This provides a natural mechanism to alleviate the coincidence problem. We investigate the dynamics of this model and show that it leads to comparable dark energy and dark matter densities today.Comment: To appear in Pramana Journal of Physics, 201

Thickening of the pulmonary artery wall in acute intramural hematoma of the ascending aorta

BACKGROUND: The occurrence of pulmonary artery obstruction in the course of acute aortic dissection is an unusual complication. The mechanism implicated is the rupture of the outer layer of the aorta and the subsequent hemorrhage into the adventitia of the pulmonary artery that causes its wall thickening and, at times, produces extrinsic obstruction of the vessel. There are no reports of this complication in acute intramural hematoma. CASE PRESENTATION: An 87-year-old woman was admitted to the hospital in shock after having had severe chest pain followed by syncope. An urgent transesophageal echocardiogram revealed the presence of acute intramural hematoma, no evidence of aortic dissection, severe pericardial effusion with cardiac tamponade, and periaortic hematoma that involved the pulmonary artery generating circumferential wall thickening of its trunk and right branch with no evidence of flow obstruction. Urgent surgery was performed but the patient died in the operating room. The post mortem examination, in the operating room, confirmed that there was an extensive hematoma around the aorta and beneath the adventitial layer of the pulmonary artery, with no evidence of flow obstruction. CONCLUSION: This is the first time that this rare complication is reported in the scenario of acute intramural hematoma and with the transesophageal echocardiogram as the diagnostic tool

Effect of Biodiversity Changes in Disease Risk: Exploring Disease Emergence in a Plant-Virus System

The effect of biodiversity on the ability of parasites to infect their host and cause disease (i.e. disease risk) is a major question in pathology, which is central to understand the emergence of infectious diseases, and to develop strategies for their management. Two hypotheses, which can be considered as extremes of a continuum, relate biodiversity to disease risk: One states that biodiversity is positively correlated with disease risk (Amplification Effect), and the second predicts a negative correlation between biodiversity and disease risk (Dilution Effect). Which of them applies better to different host-parasite systems is still a source of debate, due to limited experimental or empirical data. This is especially the case for viral diseases of plants. To address this subject, we have monitored for three years the prevalence of several viruses, and virus-associated symptoms, in populations of wild pepper (chiltepin) under different levels of human management. For each population, we also measured the habitat species diversity, host plant genetic diversity and host plant density. Results indicate that disease and infection risk increased with the level of human management, which was associated with decreased species diversity and host genetic diversity, and with increased host plant density. Importantly, species diversity of the habitat was the primary predictor of disease risk for wild chiltepin populations. This changed in managed populations where host genetic diversity was the primary predictor. Host density was generally a poorer predictor of disease and infection risk. These results support the dilution effect hypothesis, and underline the relevance of different ecological factors in determining disease/infection risk in host plant populations under different levels of anthropic influence. These results are relevant for managing plant diseases and for establishing conservation policies for endangered plant species

High energy emission from microquasars

The microquasar phenomenon is associated with the production of jets by X-ray binaries and, as such, may be associated with the majority of such systems. In this chapter we briefly outline the associations, definite, probable, possible, and speculative, between such jets and X-ray, gamma-ray and particle emission.Comment: Contributing chapter to the book Cosmic Gamma-Ray Sources, K.S. Cheng and G.E. Romero (eds.), to be published by Kluwer Academic Publishers, Dordrecht, 2004. (19 pages

GLAST: Understanding the High Energy Gamma-Ray Sky

We discuss the ability of the GLAST Large Area Telescope (LAT) to identify, resolve, and study the high energy gamma-ray sky. Compared to previous instruments the telescope will have greatly improved sensitivity and ability to localize gamma-ray point sources. The ability to resolve the location and identity of EGRET unidentified sources is described. We summarize the current knowledge of the high energy gamma-ray sky and discuss the astrophysics of known and some prospective classes of gamma-ray emitters. In addition, we also describe the potential of GLAST to resolve old puzzles and to discover new classes of sources.Comment: To appear in Cosmic Gamma Ray Sources, Kluwer ASSL Series, Edited by K.S. Cheng and G.E. Romer

Underestimated role of legume roots for soil N fertility

Research ArticleNitrogen (N) is a major fertilizing element for plants. The distribution of N in legumes is influencing the efficiency of the next crop. Nitrogen storage in legumes is actually estimated by N fixation in shoots, whereas there is little knowledge on the contribution of roots and nodules to legume N and soil N. Here, we studied the contribution of roots and nodules of grain and pasture legumes to plant N and soil N in Mediterranean fields. Experiments were run under rainfed conditions for a 2-year period in three regions of Portugal. Entire plants including top plant and visible roots and nodules were sampled at the end of the growing seasons for grain legumes, sweet and yellow lupine, and over two harvests in case of pastures. N2 fixation was measured for grain legumes and pasture legumes using 15N tracing. Our results show that aboveground N concentration did not vary among legumes, but differed in the belowground tissues. Field studies show that 7–11%of total legume N was associated with roots and nodules. Data also show an allocation of 11– 14 kg N fixed t−1 belowground dry matter in indeterminate legumes, which represents half the amount of total aboveground plant. This finding demonstrates that investigation relying only on shoot Nunderestimates the role of legumes for soil N fertilityinfo:eu-repo/semantics/publishedVersio