1,053 research outputs found

    Atributos microbiológicos do solo em área desmatada da Floresta Amazônica na jazida petrolífera do Rio Urucu, Coari-AM.

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    O objetivo do trabalho foi avaliar a qualidade do solo utilizando atributos microbiológicos em área uma área desmatada da Floresta Amazônica na jazida petrolífera do Rio Urucu no município de Coari-AM

    The Kumaraswamy-G Poisson Family of Distributions

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    For any baseline continuous G distribution, we propose a new generalized family called the Kumaraswamy-G Poisson (denoted with the prefix “Kw-GP”) with three extra positive parameters. Some special distributions in the new family such as the Kw-Weibull Poisson, Kw-gamma Poisson and Kw-beta Poisson distributions are introduced. We derive some mathematical properties of the new family including the ordinary moments, generating function and order statistics. The method of maximum likelihood is used to fit the distributions in the new family. We illustrate its potentiality by means of an application to a real data set

    Murine infection with bioluminescent Leishmania infantum axenic amastigotes applied to drug discovery

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    Leishmaniasis is an important vector-borne neglected tropical disease caused by Leishmania parasites. Current anti-Leishmania chemotherapy is unsatisfactory, justifying the continued search for alternative treatment options. Herein, we demonstrate that luciferase-expressing Leishmania infantum axenic amastigotes, unlike promastigotes, are highly infectious to BALB/c mice and thus generate a robust bioluminescent signal in target organs, such as the liver and the spleen, as early as two weeks after infection. Treatment with the reference drugs amphotericin B and miltefosine was effective at reducing parasite burdens. This model allows the assessment of treatment efficacy using whole-mouse bioluminescence imaging without the need to wait several weeks for spleen infections to be detectable by this non-invasive method. In conclusion, we propose the use of this model in an initial approach to evaluate the treatment efficacy of promising chemical entities without having to sacrifice large numbers of animals or to wait several days for a readout.We thank Carla Oliveira from i3S for the support with the statistical analysis. Part of the content of this manuscript has been released as a pre-print in BioRxiv (https://doi.org/10.1101/326355). This work was financed by FEDER - Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020 - Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT - Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior in the framework of the project POCI-01-0145-FEDER-031013 (PTDC/SAU-PAR/31013/2017). This work also received funds from: Norte-01-0145-FEDER-000012 “Structured program on bioengineered therapies for infectious diseases and tissue regeneration” of Norte Portugal Regional Operational Programme (NORTE 2020) under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (FEDER) and through the Research Unit No. 4293; Individual funding from FCT through SFRH/BD/123734/2016 (to DC), SFRH/BD/121252/2016 (to PC) and CEECIND/02362/2017 (to JT)

    Avaliação de perdas de antocianinas totais ao longo da linha de processamento de polpa de açaí pasteurizada e congelada.

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    O objetivo deste trabalho foi avaliar como o processamento em escala industrial afeta os teores de antocianinas presentes na polpa de aça

    Ultrasonication of insulin-loaded microgel particles produced by internal gelation: impact on particle's size and insulin bioactivity

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    Alginate-dextran sulfate (ADS) microgel has been used to protect insulin from gastrointestinal attack and as a carrier to promote insulin permeation through intestinal epithelium. The throughput of ADS submicron particles generation by emulsification/internal gelation is limited by its wide size distribution. The aim of this work was to study the recovery protocol influence on ADS particles through the determination of its impact on particles’ size distribution and bioactivity. ADS particles showed a wide and multimodal distribution, characterized by a high aggregation phenomenon. In an attempt to reverse particles’ tendency to aggregate and to homogenize particle size ADS populations were submitted to ultrasonication, while particle size distribution, physical and chemical stability, and the bioactivity of entrapped insulin were investigated. After ultrasonication a narrower particle population shifted to the nanoscale, with higher physical stability and significant insulin bioactivity was obtained. Emulsification internal/gelation followed by ultrasonication constituted a valid strategy to obtain ADS particles at the submicron range, with high stability and without significantly compromising insulin bioactivity, so offering promises, under previously well established conditions, to evaluate impact of ADS particle's size on biopharmaceutical and pharmacokinetics phases

    Surface functionalization of polymeric nanospheres modulates macrophage activation: Relevance in Leishmaniasis therapy

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    To characterize the production and application of carbohydrate functionalized poly(d,l-lactide-co-glycolide) (PLGA) nanospheres as immune-modulatory mediators in the treatment of visceral leishmaniasis (VL). Materials & methods: PLGA nanospheres were prepared by nanoprecipitation and surface functionalized with mannose, mannan or mannosamine moieties using a carbodiimide reaction. Flow cytometry and fluorescence microscopy revealed the interaction of these nanospheres with macrophages. Results: The nanocarriers were taken up by murine primary macrophages using clathrin-mediated endocytosis. Co-culture of macrophages with carbohydrate-functionalized nanospheres led to their activation and production of pro-inflammatory cytokines. One dose of amphotericin B-loaded on mannan-functionalized nanospheres resulted in an efficacy VL therapy. Conclusion: This approach provides a promising therapy for VL and a new therapeutic nanoplatform for obligate intracellular pathogens.This work was supported by Fundo Europeu de Desen­volvimento Regional (FEDER) funds through the Opera­tional Competitiveness Program–COMPETE and by national funds through Fundação para a Ciência e a Tecnologia un­der projects FCOMP-01-0124-FEDER-015718 (PTDC/SAU-ENB/113151/2009). D Barros was supported by FCOMP-01- 0124-FEDER-015718 (PTDC/SAU-ENB/113151/2009) project. SA Costa Lima was supported by SFRH/BPD/37880/2007 and by QREN under contract NORTE-07-0124-FEDER-000067. The authors have no other relevant affiliations or financial involve­ment with any organization or entity with a financial inter­est in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed

    Understanding resistance vs. susceptibility in visceral leishmaniasis using mouse models of Leishmania infantum Infection

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    Every year, up to 90,000 new cases of Visceral Leishmaniasis and 30,000 resultant deaths are estimated to occur worldwide. Such numbers give relevance to the continuous study of this complex form of the disease: a zoonosis and an anthroponosis; two known etiological agents (Leishmania infantum and L. donovani, respectively); with an estimated average ratio of 1 symptomatic per 10 asymptomatic individuals; and sometimes associated with atypical clinical presentations. This complexity, which results from a long co-evolutionary process involving vector-host, host-pathogen, and pathogen-vector interactions, is still not completely understood. The determinants of visceralization are not fully defined and the dichotomy resistance vs. susceptibility remains unsolved, translating into obstacles that delay the progress of global disease control. Inbred mouse models, with different susceptibility patterns to Leishmania infection, have been very useful in exploring this dichotomy. BALB/c and C57BL/6 mice were described as susceptible strains to L. donovani visceral infection, while SV/129 was considered resistant. Here, we used these three mouse models, but in the context of L. infantum infection, the other Leishmania species that cause visceral disease in humans, and dynamically compared their local and systemic infection-induced immune responses in order to establish a parallel and to ultimately better understand susceptibility vs. resistance in visceral leishmaniasis. Overall, our results suggest that C57BL/6 mice develop an intermediate "infection-phenotype" in comparison to BALB/c and SV/129 mouse strains, considering both the splenic parasite burden and the determined target organs weights. However, the immune mechanisms associated with the control of infection seem to be different in each mouse strain. We observed that both BALB/c and SV/129, but not C57BL/6 mice, show an infection-induced increase of splenic T follicular helper cells. On the other hand, differences detected in terms of CD21 expression by B cells early after infection, together with the quantified anti-Leishmania specific antibodies, suggest that SV/129 are faster than BALB/c and C57BL/6 mice in the assembly of an efficient B-cell response. Additionally, we observed an infection-induced increase in polyfunctional CD4+ T cells in the resistant SV/129 model, opposing an infection-induced increase in CD4+IL-10+ cells in susceptible BALB/c mice. Our data aligns with the observations reported for L. donovani infection and suggest that not only a single mechanism, but an interaction of several could be necessary for the control of this parasitic disease.The research leading to these results has received funding from the project NORTE-01-0145-FEDER-000012, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). PC was supported by Foundation for Science and Technology (FCT), Portugal, through the individual grant SFRH/BD/121252/2016

    Author Correction: Challenges in the serological evaluation of dogs clinically suspect for canine leishmaniasis

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    In Figure 1C, D, and E the positive and negative controls are missing. The correct Figure 1 appears below

    Avaliação de dois diferentes sistemas de criação para o conforto térmico de búfalas Murrah, criadas na Amazônia Oriental.

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    Esta pesquisa objetivou avaliar o conforto térmico de búfalas Murrah, em dois diferentes sistemas de criação: Sistemas Tradicional (ST) e Silvipastoril (SSP), na Amazônia Oriental. O experimento foi realizado na Embrapa Amazônia Oriental, em tipo climático Afi, segundo Köppen. O período experimental foi de doze meses, em dois turnos (manhã e tarde). Os animais foram inseridos no ST (n=10), composto por três piquetes, sem acesso à água para banho e sombreamento, e SSP (n=10), com sombreamento da espécie florestal Racosperma mangium. Foram aferidas variáveis meteorológicas e fisiológicas, e calculado o Índice de Conforto de Benezra (ICB), para os dois sistemas de criação, e comparados pelo Teste t (P0,05). Por disponibilizar sombreamento, o SSP propiciou melhores condições de conforto térmico para as búfalas
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