Xylanase from Fusarium heterosporum: Properties and influence of thiol compounds on xylanase activity

The properties of xylanase purified from Fusarium heterosporum that was grown in barley-brewing residue under solid-state fermentation and the effects of thiol compounds on the reactivation of the metal ion-inhibited xylanase were investigated. Xylanase was purified to homogeneity by ion exchange chromatography, and its molecular mass was estimated to be 19.5 kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH for the xylanase was 5.0, and it was stable in acidic pH (4.5 to 5.5), where it retained more than 87% of its activity after 24 h. The optimum temperature was 50°C, and it had a half-life of 53 min at 45°C. The apparent Km and Vmax values for the xylanase were 5.63 mg/ml and 800 μmol/mg/min, respectively. Ba2+, Ca2+, Mg2+ and the thiol compounds β-mercaptoethanol and dithiothreitol (DTT) enhanced xylanase activity, while Hg2+, Pb2+ and Zn2+ strongly inhibited enzyme activity. Furthermore, this xylanase had an alternative mode of regulation in the presence of thiol compounds because the enzyme was able to recover its catalytic activity after inhibition by heavy metal ions.Keywords: Hemicellulase, fungus, solid-state fermentation, barley brewing residue, thiol compoundsAfrican Journal of Biotechnology, Vol. 13(9), pp. 1047-1055, 26 February, 201

Síndrome de Torsades de Pointes: análise de casos: Torsades de Pointes Syndrome: case analysis

A Síndrome de Torsades de Pointes (TdP) é uma taquiarritmia ventricular polimórfica de pacientes com um intervalo QT longo congênito ou induzido por fármacos, cujo eletrocardiograma possui aspecto de “torção das pontas” e os sinais e sintomas característicos são síncope, palpitação ou mesmo evolução para fibrilação ventricular e morte súbita. O sexo mais frequentemente acometido é o feminino, o diagnóstico se baseia no eletrocardiograma e o tratamento preconizado é o sulfato de magnésio (MgSO4) intravenoso, a correção dos distúrbios eletrolíticos, principalmente a hipocalemia e o tratamento da causa base, na TdP farmacoinduzida. O objetivo do estudo é analisar os casos de Síndrome de Torsades de Pointes em pacientes com alterações do intervalo QT no eletrocardiograma. Trata-se de uma revisão bibliográfica integrativa, do tipo quantitativa, que utilizou as plataformas do PubMed, SciELO e Cochrane Library como bases de dados para seleção dos artigos, todos na língua inglesa. Foram utilizadas literaturas publicadas com recorte temporal de 2017 a 2022. De acordo com as literaturas analisadas, conclui-se que a TdP é uma taquiarritmia ventricular polimórfica com um mau prognóstico se não tratada precocemente com o MgSO4 intravenoso e, por ter diversas etiologias, é primordial que o diagnóstico preciso seja estabelecido de forma rápida, devido ao alto índice de mortalidade. Pacientes portadores da síndrome do QT longo congênita, bradicardia sinusal e bloqueio atrioventricular de 1º grau possuem predisposição para o desenvolvimento de TdP. Observa-se escassez na literatura a respeito das formas adequadas de prevenção da TdP, já que muitos pacientes que participam das triagens, muitas das vezes inefetivas, adquirem a síndrome após o uso de drogas que a predispõem, com prolongamento do intervalo QT, ou não sabem que possuem uma SQTL pré-existente, obrigatória para o desenvolvimento da TdP

Ciência, Crise e Mudança. 3.º Encontro Nacional de História das Ciências e da Tecnologia. ENHCT2012

III Encontro Nacional de História das Ciências e da Tecnologia. O Centro de Estudos de História e Filosofia da Ciência, organiza o 3.º Encontro Nacional de História da Ciência e da Técnica, sob o tema «Ciência, Crise e Mudança» que tem lugar na Universidade de Évora, nos dias 26, 27 e 28 de Setembro de 2012. O Primeiro Encontro Nacional de História da Ciência teve lugar em 21 e 22 Julho de 2009, no seguimento do programa de estímulo ao de¬senvolvimento da História da Ciência em Portugal e de valorização do património cultural e científico do País, lançado pelo Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) em 31 de Janeiro desse ano. A sua organização coube a investigadores do Instituto de História Contemporânea (IHC), da FCSH da UNL, e do Centro Científico e Cultural de Macau (CCCM), em cujas instalações se realizou. De en¬tre as conclusões do Encontro, destacou-se a de realizar periodicamen¬te novos Encontros Nacionais, a serem organizados de forma rotativa por diferentes centros e núcleos de investigadores. Na sequência deste Primeiro Encontro, o Centro Interuniversitário de História das Ciências e da Tecnologia (CIUHCT) organizou, entre 26 e 28 de Julho de 2010, o II Encontro, dedicado ao tema “Comunicação das Ciências e da Tecnologia em Portugal: Agentes, Meios e Audiências”. Cabe agora ao CEHFCi cumprir o que foi decidido no final deste Encontro. Na situação económica e política que hoje vivemos torna-se particularmente urgente aprofundar o estudo e o debate sobre a interação entre a Sociedade, a Ciência e a sua História. Coordenação Científica e Executiva do encontro estiveram a cargo de dois investigadores CEHFCi: Maria de Fátima Nunes, José Pedro Sousa Dia

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora