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131.
Henrique Barbosa Thais A. Costa-Silva Geanne A. Alves Conserva Adelson J. Araujo Ana Luísa L. Lordello Guilherme M. Antar Maiara Amaral Marisi G. Soares Andre G. Tempone João Henrique G. Lago 《化学与生物多样性》2021,18(4):e2001022
One new aporphine, dicentrine-β-N-oxide ( 1 ), together with five related known alkaloids dehydrodicentrine ( 2 ), predicentrine ( 3 ), N-methyllaurotetanine ( 4 ), cassythicine ( 5 ), and dicentrine ( 6 ) were isolated from the leaves of Ocotea puberula (Lauraceae). Antiprotozoal activity of the isolated compounds was evaluated in vitro against trypomastigote forms of Trypanosoma cruzi. Among the tested compounds, alkaloid 1 exhibited higher potential with EC50 value of 18.2 μM and reduced toxicity against NCTC cells (CC50>200 μM – SI>11.0), similar to positive control benznidazole (EC50 of 17.7 μM and SI=10.7). Considering the promising results of dicentrine-β-N-oxide ( 1 ) against trypomastigotes, the mechanism of parasite death caused by this alkaloid was investigated. As observed, this compound reached the plasma membrane electric potential directly after 2 h of incubation and triggered mitochondrial depolarization, which probably leads to trypomastigote death. Therefore, dicentrine-β-N-oxide ( 1 ), reported for the first time in this work, can contribute to future works for the development of new trypanocidal agents. 相似文献
132.
Cluster Computing - This paper proposes a new version of the power of two choices, SQ(d), load balancing algorithm. This new algorithm improves the performance of the classical model based on the... 相似文献
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134.
Christian Reimold Herve Joel Defeu Soufo Felix Dempwolff Peter L. Graumann 《Molecular biology of the cell》2013,24(15):2340-2349
The maintenance of rod-cell shape in many bacteria depends on actin-like MreB proteins and several membrane proteins that interact with MreB. Using superresolution microscopy, we show that at 50-nm resolution, Bacillus subtilis MreB forms filamentous structures of length up to 3.4 μm underneath the cell membrane, which run at angles diverging up to 40° relative to the cell circumference. MreB from Escherichia coli forms at least 1.4-μm-long filaments. MreB filaments move along various tracks with a maximal speed of 85 nm/s, and the loss of ATPase activity leads to the formation of extended and static filaments. Suboptimal growth conditions lead to formation of patch-like structures rather than extended filaments. Coexpression of wild-type MreB with MreB mutated in the subunit interface leads to formation of shorter MreB filaments and a strong effect on cell shape, revealing a link between filament length and cell morphology. Thus MreB has an extended-filament architecture with the potential to position membrane proteins over long distances, whose localization in turn may affect the shape of the cell wall. 相似文献
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136.
Victoria E. Santos Almudena Alcón Ana B. Martín Emilio Gómez Felix Garcia-Ochoa 《Biocatalysis and Biotransformation》2013,31(2-4):286-294
The influence of operational conditions (pH, temperature and oxygen transfer rate) on the initial reaction rates of the four reactions involved in the 4S biodesulfurization route of dibenzothiophenes (DBT) has been studied. The bioprocess was carried out using a genetically modified organism, Pseudomonas putida CECT 5279. The rates of the four reactions were calculated from the rates of production of different compounds involved in the 4S pathway, by matrix manipulation. The initial (zero time) reaction rates showed a slight dependence on oxygen transfer rate. Temperature and pH were optimal at 30°C and 9, respectively, temperature being the most important variable. This study also identifies the last reaction as the limiting step in the pathway. 相似文献
137.
Hans Van Oosterwyck José Felix Rodríguez Manuel Doblaré José Manuel García Aznar 《Computer methods in biomechanics and biomedical engineering》2013,16(9):1002-1012
Actin filaments are a major component of the cytoskeleton and play a crucial role in cell mechanotransduction. F-actin networks can be reconstituted in vitro and their mechanical behaviour has been studied experimentally. Constitutive models that assume an idealised network structure, in combination with a non-affine network deformation, have been successful in capturing the elastic response of the network. In this study, an affine network deformation is assumed, in which we propose an alternative 3D finite strain constitutive model. The model makes use of a micro-sphere to calculate the strain energy density of the network, which is represented as a continuous distribution of filament orientations in space. By incorporating a simplified sliding mechanism at the filament-to-filament junctions, premature filament locking, inherent to affine network deformation, could be avoided. The model could successfully fit experimental shear data for a specific cross-linked F-actin network, demonstrating the potential of the novel model. 相似文献
138.
Andre Vosloo Anél Laas Dalene Vosloo 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2013,164(1):192-199
Marine invertebrates have evolved multiple responses to naturally variable environmental oxygen, all aimed at either maintaining cellular oxygen homeostasis or limiting cellular damage during or after hypoxic or hyperoxic events. We assessed organismal (rates of oxygen consumption and ammonia excretion) and cellular (heat shock protein expression, anti-oxidant enzymes) responses of juvenile and adult abalone exposed to low (~ 83% of saturation), intermediate (~ 95% of saturation) and high (~ 115% of saturation) oxygen levels for one month. Using the Comet assay, we measured DNA damage to determine whether the observed trends in the protective responses were sufficient to prevent oxidative damage to cells. Juveniles were unaffected by moderately hypoxic and hyperoxic conditions. Elevated basal rates of superoxide dismutase, glutathione peroxidase and catalase were sufficient to prevent DNA fragmentation and protein damage. Adults, with their lower basal rate of anti-oxidant enzymes, had increased DNA damage under hypoxic and hyperoxic conditions, indicating that the antioxidant enzymes were unable to prevent oxidative damage under hypoxic and hyperoxic conditions. The apparent insensitivity of juvenile abalone to decreased and increased oxygen might be related to their life history and development in algal and diatom biofilms where they are exposed to extreme diurnal fluctuations in dissolved oxygen levels. 相似文献
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140.
Jagar?JasemEmail author Kawa?Marof Adnan?Nawar Yosra?Khalaf Sirwan?Aswad Faisal?Hamdani Monirul?Islam Andre?Kalil 《BMC neurology》2013,13(1):195