242 research outputs found

    A contribution to the knowledge of Quadraseta brasiliensis Goff and Gettinger, 1989 (Trombidiformes: Trombiculidae), with description of the deutonymph instar

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    In the Neotropical region the genus Quadraseta Brennan, 1970, includes 14 species, with ectoparasitic habits during the larval stage. Quadraseta brasiliensis Goff and Gettinger, 1989, was described from larvae collected on the rodent Hylaeamys megacephalus (Fisher), cited as Oryzomys capito (Olfers). According to these authors, the holotype was deposited in the Museu de Zoologia da Universidade de São Paulo and the paratypes were deposited in three other collections: Bernice Pauahi Bishop Museum, Sam Noble Oklahoma Museum of Natural History and United States National Museum of Natural History, however, no type specimens were found in any of these museums. Here we redescribe the larva, describe the deutonymph instar obtained from field-collected larvae, and report new hosts and localities for this species in Brazil. In addition we provide sequences of the 18S ribosomal RNA gene for this species

    The evolution of ultraviolet emission lines from the circumstellar material surrounding SN 1987A

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    The presence of narrow high-temperature emission lines from nitrogen-rich gas close to SN 1987A has been the principal observational constraint on the evolu- tionary status of the supernova's progenitor. A new analysis of the complete five-year set of low and high resolution IUE ultraviolet spectra of SN 1987A (1987.2--1992.3) provide fluxes for the N V 1240, N IV] 1486, He II 1640, OIII] 1665, NIII] 1751, and CIII] 1908 lines with significantly reduced random and systematic errors and reveals significant short-term fluctuations in the light curves. The N V, N IV] and N III] lines turn on sequentially over 15 to 20 days and show a progression from high to low ionization potential, implying an ioni- zation gradient in the emitting region. The line emission turns on suddenly at 83+/-4 days after the explosion, as defined by N IV]. The N III] line reaches peak luminosity at 399+/-15 days. A ring radius of (6.24+/-0.20)E{17} cm and inclination of 41.0+/-3.9 is derived from these times, assuming a circular ring. The probable role of resonant scattering in the N V light curve introduces systematic errors that leads us to exclude this line from the timing analysis. A new nebular analysis yields improved CNO abundance ratios N/C=6.1+/-1.1 and N/O=1.7+/-0.5, confirming the nitrogen enrichment found in our previous paper. From the late-time behavior of the light curves we find that the emission origi- nates from progressively lower density gas. We estimate the emitting mass near maximum (roughly 400 days) to be roughly 4.7E{-2} solar masses, assuming a filling factor of unity and an electron density of 2.6E4 cm^{-3}. These results are discussed in the context of current models for the emission and hydrodynamics of the ring.Comment: 38 pages, AASTeX v.4.0, 13 Postscript figures; ApJ, in pres

    Biological activity differences between TGF-β1 and TGF-β3 correlate with differences in the rigidity and arrangement of their component monomers

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    [Image: see text] TGF-β1, -β2, and -β3 are small, secreted signaling proteins. They share 71–80% sequence identity and signal through the same receptors, yet the isoform-specific null mice have distinctive phenotypes and are inviable. The replacement of the coding sequence of TGF-β1 with TGF-β3 and TGF-β3 with TGF-β1 led to only partial rescue of the mutant phenotypes, suggesting that intrinsic differences between them contribute to the requirement of each in vivo. Here, we investigated whether the previously reported differences in the flexibility of the interfacial helix and arrangement of monomers was responsible for the differences in activity by generating two chimeric proteins in which residues 54–75 in the homodimer interface were swapped. Structural analysis of these using NMR and functional analysis using a dermal fibroblast migration assay showed that swapping the interfacial region swapped both the conformational preferences and activity. Conformational and activity differences were also observed between TGF-β3 and a variant with four helix-stabilizing residues from TGF-β1, suggesting that the observed changes were due to increased helical stability and the altered conformation, as proposed. Surface plasmon resonance analysis showed that TGF-β1, TGF-β3, and variants bound the type II signaling receptor, TβRII, nearly identically, but had small differences in the dissociation rate constant for recruitment of the type I signaling receptor, TβRI. However, the latter did not correlate with conformational preference or activity. Hence, the difference in activity arises from differences in their conformations, not their manner of receptor binding, suggesting that a matrix protein that differentially binds them might determine their distinct activities

    Severe Neonatal Cholestasis as an Early Presentation of McCune- Albright Syndrome

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    McCune-Albright syndrome (MAS) is a rare genetic disorder characterized by café-au-lait macules, polyostotic fibrous dysplasia and multiple endocrinopathies. Liver involvement, although described, is a rare complication. We review the case of a child with MAS whose initial presentation was characterized by severe neonatal cholestasis. The case demonstrates a severe phenotype of persistent cholestasis in MAS requiring liver transplantation. This phenotype has been previously considered to be a more benign feature. This case highlights the importance of consideration of MAS as an uncommon but important cause of neonatal cholestasis. Early diagnosis may allow for prompt recognition and treatment of other endocrinopathies

    Removal of gaseous toluene using immobilized Candida tropicalis in a fluidized bed bioreactor

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    A pure yeast strain Candida tropicalis was immobilized on the matrix of powdered activated carbon, sodium alginate, and polyethylene glycol (PSP beads). The immobilized beads were used as fluidized material in a bioreactor to remove toluene from gaseous stream. Applied toluene loadings were 15.4 and 29.8 g/m3 h in Step 1 and Step 2, respectively, and toluene removal was found above 95% during the entire operation. A continuous pH decline was observed and pH of the suspension was just above 6 in Step 2 but no adverse effects on treatment efficiency were observed. The CO2 yield values were found to be 0.57 and 0.62 g-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}CCO2/g-Ctoluene C_{{{\text{CO}}_{2} }} /{\text{g-}}C_{\text{toluene}} \end{document} in Step 1 and Step 2, respectively. These values indicate that a major portion of toluene-carbon was channeled to yeast respiration even at higher toluene loading. In conclusion, immobilized C. tropicalis can be used as a fluidized material for enhanced degradation of gaseous toluene

    Latin American chronic urticaria registry (CUR) contribution to the understanding and knowledge of the disease in the region

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    Chronic urticaria (CU) has a widespread spectrum on causal or exacerbating factors, clinical manifestations, therapeutic response and quality of life affectation. Registries are useful tools in several real-life diagnosis and management approach. We aimed to evaluate the characteristics of CU patients living in Latin America through an original cross-sectional registry with data entered by regional allergologists. Results: Three hundred patients were included, being 72% female, with median age of 36 years (1\u201385) and 20 months of CU median evolution time. The cause of CU was reported as unknown in 72% of them. Thirty-nine percent of suspected cases presented positive serology for Mycoplasma, positive autologous serum skin test (ASST) was reported in 47%, and occasional presence of thyroid or antinuclear autoantibodies and parasites. The impact of pruritus in their quality of life was moderate to severe in 60% of patients, with almost 3 out of four patients having partial or lack of urticaria control with anti-histamines. Conclusions: Our registry provides retrospective data on the real-life assistance of a large number of patients from the region. Continuous search for associated conditions and better treatment possibilities are needed, in order to control the significant impact on quality of life and the length of disease

    Planetary nebulae and H II regions in the spiral galaxy NGC 300: Clues on the evolution of abundance gradients and on AGB nucleosynthesis

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    We have obtained deep spectra of 26 planetary nebulae (PNe) and 9 compact H II regions in the nearby spiral galaxy NGC 300, and analyzed them together with those of the giant H II regions previously observed. We have determined the physical properties of all these objects and their He, N, O, Ne, S and Ar abundances in a consistent way. We find that, globally, compact H II regions have abundance ratios similar to those of giant H II regions, while PNe have systematically larger N/O ratios and similar Ne/O and Ar/O ratios. We demonstrate that the nitrogen enhancement in PNe cannot be only due to second dredge-up in the progenitor stars, since their initial masses are around 2–2.5 M⊙. An extra mixing process is required, perhaps driven by stellar rotation. Concerning the radial abundance distribution, PNe behave differently from H II regions: in the central part of the galaxy their average O/H abundance ratio is 0.15 dex smaller. Their abundance dispersion at any galactocentric radius is significantly larger than that shown by H II regions and many of them have O/H values higher than H II regions at the same galactocentric distance. This suggests that not only nitrogen, but also oxygen is affected by nucleosynthesis in the PN progenitors, by an amount which depends at least on the stellar rotation velocity and possibly other parameters. The formal O/H, Ne/H and Ar/He abundance gradients from PNe are significantly shallower than those from H II regions. We argue that this indicates a steepening of the metallicity gradient in NGC 300 during the last Gyr, rather than an effect of radial stellar motions, although the large observed dispersion makes this conclusion only tentative

    Type-Specific HPV Prevalence in Cervical Cancer and High-Grade Lesions in Latin America and the Caribbean: Systematic Review and Meta-Analysis

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    BACKGROUND: Cervical cancer is a major public health problem in Latin America and the Caribbean (LA&C), showing some of the highest incidence and mortality rates worldwide. Information on HPV type distribution in high-grade cervical lesions (HSIL) and invasive cervical cancer (ICC) is crucial to predict the future impact of HPV16/18 vaccines and screening programmes, and to establish an appropriate post-vaccinal virologic surveillance. The aim was to assess the prevalence of HPV types in HSIL and ICC in studies in LA&C. METHODS AND FINDINGS: We performed a systematic review, following the MOOSE guidelines for systematic reviews of observational studies, and the PRISMA statement for reporting systematic reviews and meta-analyses. Inclusion criteria were at least ten cases of HSIL/ICC, and HPV-type elicitation. The search, without language restrictions, was performed in MEDLINE, Cochrane Library, EMBASE, LILACS from inception date to December 2009, proceedings, reference lists and consulting experts. A meta-analysis was performed using arc-sine transformations to stabilize the variance of simple proportions. Seventy-nine studies from 18 countries were identified, including 2446 cases of HSIL and 5540 of ICC. Overall, 46.5% of HSIL cases harbored HPV 16 and 8.9% HPV18; in ICC, 53.2% of cases harbored HPV 16 and 13.2% HPV 18. The next five most common types, in decreasing frequency, were HPV 31, 58, 33, 45, and 52. Study's limitations comprise the cross-sectional design of most included studies and their inherent risk of bias, the lack of representativeness, and variations in the HPV type-specific sensitivity of different PCR protocols. CONCLUSIONS: This study is the broadest summary of HPV type distribution in HSIL and ICC in LA&C to date. These data are essential for local decision makers regarding HPV screening and vaccination policies. Continued HPV surveillance would be useful, to assess the potential for changing type-specific HPV prevalence in the post-vaccination era in Latin America

    Kuhnian revolutions in neuroscience: the role of tool development.

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    The terms "paradigm" and "paradigm shift" originated in "The Structure of Scientific Revolutions" by Thomas Kuhn. A paradigm can be defined as the generally accepted concepts and practices of a field, and a paradigm shift its replacement in a scientific revolution. A paradigm shift results from a crisis caused by anomalies in a paradigm that reduce its usefulness to a field. Claims of paradigm shifts and revolutions are made frequently in the neurosciences. In this article I will consider neuroscience paradigms, and the claim that new tools and techniques rather than crises have driven paradigm shifts. I will argue that tool development has played a minor role in neuroscience revolutions.The work received no fundin
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