11,204 research outputs found
Novel Inhibitors for Isocitrate Lyase as a Potent Antitubercular Agent for Mycobacterium Tuberculosis
Introduction: Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB). TB claimed 1.4 million lives in 2019. It is estimated that one-quarter of the worldâs population is infected with latent TB. Current first- and second-line drugs used to treat TB require adherence to an extended period of therapy (at least six months) and do not target latent TB. It has been shown that the enzyme isocitrate lyase (ICL) is essential for the survival and persistence of Mtb in latent TB. ICL plays an important role in two metabolic pathways required during TB latency, the glyoxylate and methylcitrate cycle. ICL is absent in humans, and therefore, it is considered a promising drug target. Herein, is reported a novel family of ICL inhibitors that is effective in vitro against both the enzyme and Mtb.
Methods: The His-tagged ICL1 enzyme was expressed using E. coli as a host and purified by Ni-NTA chromatography. The recombinant enzyme was used to set up crystallisation trials and in vitro enzymatic assay was performed on ICL1 inhibitors. The synthesis of D/L-threo-2-methylisocitrate and the methylation of five other drug candidates were described. Both co-crystallisation and soaking techniques were performed to obtain an ICL1:CL-54-04 complex crystal, whose structure was solved. The CL-54 drug family was tested against Mtb. A checkerboard assay was utilised to test the combinatory effect of CL-54-04 with rifampicin or bedaquiline in both glycerol and propionate media. To investigate the role of acetate metabolism in drug tolerance, ÎpckA, ICL knock-down and ÎprpD Mtb mutants were assessed.
Results: Seven new conditions to crystallise ICL1 were identified, and eleven drugs were tested against the isolated enzyme. A promising new family of drugs have been identified as the most potent ICL1 inhibitors reported to date. One of the analogues, CL-54-04, had a bacteriostatic effect at 10 ÎŒM and a bactericidal effect at 100 ÎŒM against Mtb in vitro. A drug combination screening of CL-54-04 with rifampicin or bedaquiline led to an additive effect in the checkerboard assay and a significant impact in the colony-forming unit assay. The role of fatty acid metabolism in drug tolerance was investigated by testing three central carbon metabolism mutant strains against isoniazid.
Discussion: From the three CL-54 analogues tested, only CL-54-04 caused a bactericidal effect against Mtb. A solved ICL1:CL-54-04 complex crystal structure showed that the catalytic loop had a distinctive move of 13.8 Ă
, suggesting that the binding of ICL with CL-54-04 leads to a close conformation of the active site. A superimposition of the solved ICL1:CL-54-04 complex and the ICL1 structure alignment with 3-nitropropionate demonstrates that CL-54-04 inhibitor binds and causes the same conformational changes as 3-nitropropionate. Using metabolomics analysis, the combination of rifampicin and CL-54-04 causes an accumulation of the methylcitrate cycle metabolites in propionate media, suggesting that the ICL has been inhibited. Fatty acid as a sole carbon source showed to increase the drug tolerance of all three Mtb mutants against isoniazid.
Conclusion: A new drug family has been identified as lead compounds against ICL. The estimated IC50 of CL-54-01 is approximately half of the 3-nitropropionamide, and it causes the exact conformational change to the enzyme as 3-nitropropionate (the analogue of 3-nitropropionamide). These findings suggest that this drug family are the most promising ICL1 inhibitors reported to date
LIMO EEG: A Toolbox for hierarchical LInear MOdeling of ElectroEncephaloGraphic data
Magnetic- and electric-evoked brain responses have traditionally been analyzed by comparing the peaks or mean amplitudes of signals from selected channels and averaged across trials. More recently, tools have been developed to investigate single trial response variability (e.g., EEGLAB) and to test differences between averaged evoked responses over the entire scalp and time dimensions (e.g., SPM, Fieldtrip). LIMO EEG is a Matlab toolbox (EEGLAB compatible) to analyse evoked responses over all space and time dimensions, while accounting for single trial variability using a simple hierarchical linear modelling of the data. In addition, LIMO EEG provides robust parametric tests, therefore providing a new and complementary tool in the analysis of neural evoked responses
The future of spaceborne altimetry. Oceans and climate change: A long-term strategy
The ocean circulation and polar ice sheet volumes provide important memory and control functions in the global climate. Their long term variations are unknown and need to be understood before meaningful appraisals of climate change can be made. Satellite altimetry is the only method for providing global information on the ocean circulation and ice sheet volume. A robust altimeter measurement program is planned which will initiate global observations of the ocean circulation and polar ice sheets. In order to provide useful data about the climate, these measurements must be continued with unbroken coverage into the next century. Herein, past results of the role of the ocean in the climate system is summarized, near term goals are outlined, and requirements and options are presented for future altimeter missions. There are three basic scientific objectives for the program: ocean circulation; polar ice sheets; and mean sea level change. The greatest scientific benefit will be achieved with a series of dedicated high precision altimeter spacecraft, for which the choice of orbit parameters and system accuracy are unencumbered by requirements of companion instruments
Identity ambivalences of the Eurasian Macanese : historical dynamics, political regimes and food practices
This article focuses on the phenomenological experience of identity ambivalence arising from the Eurasian Macanese community through their phenomenological experience of identity ambivalence. Our thematic framework includes the structural impact of colonial and post colonial political regimes in Macao, historical influences on contemporary identity and sociocultural expressions of creolisation. It is argued that the Macanese people illustrate the memory of the ambivalent encounter between the two extremities of the Eurasia (China and Portugal) which started in the 16th-c. and never ceased moving forces to the present day. Furthermore, in the context of fieldwork with the Macanese community in Portugal, an ethnographic approach helps reveal the ambivalent dynamics of similarities and differentiation with respect to food practices and commensality as expressed over dinner by a group of close friends in Lisbon.Cet article preÌsente une eÌtude de cas des macanais euro-asiatiques â ethniquement et culturellement meÌtisseÌs â du point de vue de lâexpeÌrience pheÌnomeÌnologique reÌsul- tant de leur identiteÌ ambivalente. Les questions traiteÌes ici englobent les forces struc- turelles des reÌgimes politiques coloniaux et post-coloniaux aÌ Macao, les influences historiques sur les identiteÌs contemporaines et les expressions socioculturelles de la creÌolisation. On fait valoir que les macanais repreÌsentent la meÌmoire dâune rencontre ambivalente entre les deux extreÌmiteÌs de lâEurasie (Chine et Portugal) qui depuis le XVIe s. jusquâaÌ nos jours nâont jamais cesseÌ de mesurer leurs forces. Dans le cadre dâune enqueÌte de terrain meneÌe aupreÌs de la communauteÌ macanaise au Portugal, lâapproche ethnographique a aussi permis de reÌveÌler les dynamiques ambivalentes de similariteÌ et de diffeÌrence en matieÌre de commensaliteÌ et de pratiques alimentaires exprimeÌes par un groupe dâamis proches lors dâun diÌner aÌ Lisbonne.Este artigo analisa o estudo de caso dos macaenses euro-asiĂĄticos â indivĂduos Ă©tnica e culturalmente mestiços â do ponto de vista da experiĂȘncia fenomenolĂłgica resultante da sua identidade ambivalente. As temĂĄticas aqui exploradas abrangem as forças estruturais dos regimes polĂticos coloniais e pĂłs-coloniais em Macau, as influĂȘncias histĂłricas sobre as identidades contemporĂąneas e as expressĂ”es socioculturais da crioulização desenvolvidas. Ă argumentado que os macaenses representam a memĂłria de um encontro ambivalente entre os dois extremos da EurĂĄsia, um processo com inĂcio no sĂ©culo XVI e que nunca parou de medir forças atĂ© aos dias de hoje. Adotou-se ainda uma perspetiva etnogrĂĄfica para abordar o conjunto de dinĂąmicas ambivalentes de semelhança e diferença em relação Ă s prĂĄticas alimentares e de comensalidade, expressas por um grupo de amigos Ăntimos no decorrer de um jantar em Lisboa.info:eu-repo/semantics/publishedVersio
Tools for the automation of large distributed control systems
The new LHC experiments at CERN will have very large numbers of channels to operate. In order to be able to configure and monitor such large systems, a high degree of parallelism is necessary. The control system is built as a hierarchy of sub-systems distributed over several computers. A toolkit - SMI++, combining two approaches: finite state machines and rule-based programming, allows for the description of the various sub-systems as decentralized deciding entities, reacting is real-time to changes in the system, thus providing for the automation of standard procedures and for the automatic recovery from error conditions in a hierarchical fashion. In this paper we will describe the principles and features of SMI++ as well as its integration with an industrial SCADA tool for use by the LHC experiments and we will try to show that such tools, can provide a very convenient mechanism for the automation of large scale, high complexity, applications
Medicinal and Aromatic Plants collecting missions in Portugal
Abstract: Medicinal and aromatic plants (MAP) are used in all civilizations and cultures and have always played a key role in health care systems worldwide. These plants constitute a major part of the flora, which provide raw materials that are primarily used for therapeutic, aromatic and/or culinary purposes, as components of medicinal and cosmetics products and other natural health products. They are also the starting materials for value-added processed natural ingredients such as essential oils, dry and liquid extracts and oleoresins. Portugal has given rise to very diverse environmental habitats, is cradle to a rich flora, comprising 3,995 described taxa, 500 of which are of aromatic and/or medicinal potential. Some of these species are endemic, sometimes with very vulnerable ecological niches. Plant genetic resourcesâ collecting is a fundamental activity, widely used in ex situ conservation. Between 1990 and 2014, the Banco PortuguĂȘs de Germoplasma Vegetal (BPGV), carried out national and international MAP collecting missions, which resulted in the ex situ conservation of 1,606 accessions. The main focus of this communication is to demonstrate the valuable contribution of those collecting missions in MAP genetic diversity conservation and evaluation.
Revised Coordinates and Proper Motions of the Stars in the Luyten Half-Second Catalogue
We present refined coordinates and proper motion data for the high proper
motion (HPM) stars in the Luyten Half-Second (LHS) catalogue. The positional
uncertainty in the original Luyten catalogue is typically >10" and is often
>30". We have used the digital scans of the Palomar Observatory Sky Survey
(POSS) I and POSS II plates to derive more accurate positions and proper
motions of the objects. Out of the 4470 candidates in the LHS catalogue, 4323
objects were manually re-identified in the POSS I and POSS II scans. A small
fraction of the stars were not found due to the lack of finder charts and
digitized POSS II scans. The uncertainties in the revised positions are
typically ~2", but can be as high as ~8" in a few cases; this is a large
improvement over the original data. Cross-correlation with the Tycho-2 and
Hipparcos catalogues yielded 819 candidates (with m_R < 12). For these brighter
sources, the position and proper motion data have been replaced with the more
accurate Tycho/Hipparcos data. In total, we have revised proper motion
measurements and coordinates for 4040 stars and revised coordinates for 4330
stars, which are presented here.Comment: 108 pages. Accepted for Publication in ApJ Suppl. Some errors caused
by the transcription errors in the original LHS catalogue have been corrected
in this resubmission. The most current version of the catalogue is also
available online at http://www.stsci.edu/~ksahu/lh
Influence of tow duration and tooth length on the number of damaged razor clams Ensis siliqua
The incidence of shell damage due to dredging was studied in the bivalve Ensis siliqua off Lagos, on the south coast of Portugal. Three tow durations (1, 3 and 5 min) and 2 tooth lengths (30 and 40 cm) were investigated. Both factors affected the proportion of damaged individuals. The increase of tooth length results in lower proportions of damaged razor clams. An increase in tow duration increased total numbers caught but also increased the proportion of damaged clams. It is suggested that dredges with 40 cm teeth and tows of 1 min duration should be used in this fishery, although experiments should be undertaken in order to evaluate the environmental and ecological impact of dredges
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