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排序方式: 共有269条查询结果,搜索用时 78 毫秒
131.
Gomes A Fernandes E Garcia MB Silva AM Pinto DC Santos CM Cavaleiro JA Lima JL 《Bioorganic & medicinal chemistry》2008,16(17):7939-7943
2-Styrylchromones (2-SC) are a chemical family of oxygen heterocyclic compounds, vinylogues of flavones (2-phenylchromones), whose occurrence in nature has been reported. Recently, several 2-SC derivatives were demonstrated to have antioxidant properties, namely, xanthine oxidase inhibition, hepatoprotection against pro-oxidant agents in cellular and non-cellular systems and scavenging activity against reactive oxygen and reactive nitrogen species (ROS and RNS). Considering these antioxidant properties, it may be hypothesised that the electrochemical redox behaviour of 2-SC contributes significantly to their activity. To test this hypothesis, the electrochemical behaviour of different 2-SC was studied, together with a number of flavonoids with well-known antioxidant activities, by cyclic voltammetry, and the results correlated to their ability to scavenge ROS and RNS. The results obtained showed that 2-SC with a catecholic B-ring have a low oxidation peak potential corresponding to the oxidation of the 3',4'-OH (catechol) moiety. The compounds with a phenolic B-ring have a common peak, with oxidation potential values of about +0.4/+0.5 V versus Ag/AgCl, corresponding to the oxidation of the 4'-OH. The oxidation of the hydroxyl substituents in the A-ring generated peaks of higher potentials (+0.7/+0.8 V vs Ag/AgCl). The results from the scavenging assays were in agreement with those obtained from the cyclic voltammetry, that is, higher scavenging effects corresponded to lower values of oxidation potentials, with significant correlation coefficients. The values obtained for the studied flavonoids are in accordance with the literature, and reflect their relative antioxidant activity, when compared to the studied 2-SC. Thus, in this family of compounds, oxidation potentials obtained by cyclic voltammetry seem to be applicable as a general indicator of radical scavenging activity. 相似文献
132.
A model for a population-game with multiple asymmetry is studied, in which the participants are assumed to be different from one another both in size and in status as owners or non-owners of a territory. Only owners can reproduce, hence natural selection is assumed to operate in favor of the increase of ownership-time. Conditions for the evolutionary stability of the Bourgeois Principle of owner-priority, despite difference in body size, are characterized. It is shown that ownership-priority tends to be at least partially replaced by strength-priority as the availability of habitats, the expected longevity of potential intruders and the harm inflicted on the loser of an aggressive confrontation decrease, and as the expected longevity of the owner increases. It is further established that the combined effect of all these parameters can be characterized by a single parameter, referred to as the concord coefficient of the population. Finally, when this parameter reaches a certain critical level, only strength-priority can prevail. If the concord coefficient decreases below this critical level, no priority-rule can remain stable in the population, in which case aggressive confrontations cannot be avoided, at least in certain situations. In this case, it is shown that aggression emerges first among low-rank individuals. 相似文献
133.
134.
Cryopreservation of seabream (Sparus aurata) spermatozoa 总被引:3,自引:0,他引:3
The aim of this research was to optimize protocols for freezing spermatozoa of seabream (Sparus aurata). All the phases of the cryopreservation procedure (sampling, choosing the cryoprotective extender, cooling, freezing, and thawing) were studied in relation to the species of spermatozoa under examination, so as to be able to restore on thawing the morphological and physiological characteristics of fresh semen. Seabream spermatozoa were collected by stripping and transported to the laboratory chilled (0-2 degrees C). Five cryoprotectants, dimethyl sulfoxide (Me(2)SO), ethylene glycol (EG), 1,2-propylene glycol (PG), glycerol, and methanol, were tested at concentrations between 5 and 15% by volume to evaluate their effect on the motility of semen exposed for up to 30 min at 26 degrees C. The less toxic cryoprotectants, 10% EG, 10% PG, and 5% Me(2)SO, respectively, were added to 1% NaCl to formulate the extenders for freezing. The semen was diluted 1:6 with the extender, inserted into 0.25-ml plastic straws by Pasteur pipette, and frozen using a cooling rate of either 10 or 15 degrees C/min to -150 degrees C followed by transfer and storage in liquid nitrogen (-196 degrees C). The straws were thawed at 15 degrees C/s. On thawing, the best motility was obtained with 5% Me(2)SO, although both 10% PG and EG showed good results; no differences were found between the two freezing gradients, although semen frozen with the 10 degrees C/min gradient showed a slightly higher and more prolonged motility. 相似文献
135.
Norman Morrison Dan Bearden Jacob G. Bundy Tim Collette Felicity Currie Matthew P. Davey Nathan S. Haigh David Hancock Oliver A. H. Jones Simone Rochfort Susanna-Assunta Sansone Dalibor Štys Quincy Teng Dawn Field Mark R. Viant 《Metabolomics : Official journal of the Metabolomic Society》2007,3(3):203-210
136.
Oliver Fiehn Don Robertson Jules Griffin Mariet van der Werf Basil Nikolau Norman Morrison Lloyd W. Sumner Roy Goodacre Nigel W. Hardy Chris Taylor Jennifer Fostel Bruce Kristal Rima Kaddurah-Daouk Pedro Mendes Ben van Ommen John C. Lindon Susanna-Assunta Sansone 《Metabolomics : Official journal of the Metabolomic Society》2007,3(3):175-178
In 2005, the Metabolomics Standards Initiative has been formed. An outline and general introduction is provided to inform
about the history, structure, working plan and intentions of this initiative. Comments on any of the suggested minimal reporting
standards are welcome to be sent to the open email list Msi-workgroups-feedback@lists.sourceforge.net 相似文献
137.
Laurence Flori Katayoun Moazami‐Goudarzi Vronique Alary Abdelillah Araba Ismaïl Boujenane Nadjet Boushaba Franois Casabianca Sara Casu Roberta Ciampolini Armelle Coeur D'Acier Corinne Coquelle Juan‐Vicente Delgado Ahmed El‐Beltagi Georgia Hadjipavlou Emmanuelle Jousselin Vincenzo Landi Anne Lauvie Philippe Lecomte Christina Ligda Caroline Marinthe Amparo Martinez Salvatore Mastrangelo Dalal Menni Charles‐Henri Moulin Mona‐Abdelzaher Osman Olivier Pineau Baldassare Portolano Clementina Rodellar Nadhira Saïdi‐Mehtar Tiziana Sechi Guilhem Sempr Sophie Thvenon Dimitrios Tsiokos Denis Laloë Mathieu Gautier 《Molecular ecology》2019,28(5):1009-1029
Domestic species such as cattle (Bos taurus taurus and B. t. indicus) represent attractive biological models to characterize the genetic basis of short‐term evolutionary response to climate pressure induced by their post‐domestication history. Here, using newly generated dense SNP genotyping data, we assessed the structuring of genetic diversity of 21 autochtonous cattle breeds from the whole Mediterranean basin and performed genome‐wide association analyses with covariables discriminating the different Mediterranean climate subtypes. This provided insights into both the demographic and adaptive histories of Mediterranean cattle. In particular, a detailed functional annotation of genes surrounding variants associated with climate variations highlighted several biological functions involved in Mediterranean climate adaptation such as thermotolerance, UV protection, pathogen resistance or metabolism with strong candidate genes identified (e.g., NDUFB3, FBN1, METTL3, LEF1, ANTXR2 and TCF7). Accordingly, our results suggest that main selective pressures affecting cattle in Mediterranean area may have been related to variation in heat and UV exposure, in food resources availability and in exposure to pathogens, such as anthrax bacteria (Bacillus anthracis). Furthermore, the observed contribution of the three main bovine ancestries (indicine, European and African taurine) in these different populations suggested that adaptation to local climate conditions may have either relied on standing genomic variation of taurine origin, or adaptive introgression from indicine origin, depending on the local breed origins. Taken together, our results highlight the genetic uniqueness of local Mediterranean cattle breeds and strongly support conservation of these populations. 相似文献
138.
Rubio J Calderón JS Flores A Castroa C Céspedes CL 《Zeitschrift für Naturforschung. C, Journal of biosciences》2005,60(9-10):711-716
Fractionation with n-hexane/ethyl acetate (1:1 v/v) by open column chromatography of the oleoresin from Pinus oocarpa Schiede yielded two diterpenes, pimaric acid (1) and dehydroabietic acid (5), the sesquiterpene longifolene (3) and a diterpenic mixture containing pimaric acid (1), isopimaric acid (4) and dehydroabietic acid (5). Subsequently, the isolated compounds, the mixture of 1, 4 and 5, the oleoresin and the dehydroabietic acid methyl ester (2), were tested in vitro against epimastigotes of Trypanosoma cruzi, the causative agent of Chagas disease. The most active compounds were 1, 3 and the oleoresin, being as active as nifurtimox, a drug effective in the treatment of acute infection by American trypanosomiasis and used in this work as positive control. 相似文献
139.
Siniscalchi A Marino S Marani L Piubello C Bianchi C Selvatici R 《Neurochemistry international》2005,46(2):117-125
Glutamate-induced changes in the subcellular distribution of protein kinase C isoforms and in the intracellular calcium concentration were investigated in rat primary cortical neurons. Western blot analysis of protein kinase C isoforms (alpha, beta1, beta2, gamma, delta, epsilon, zeta and theta), performed 30 min after a 10 min treatment with 30 microM glutamate, revealed a decrease in the total beta1 (-24%) and beta2 (-40%) isoform levels, without any significant change in any of the other isozymes. All conventional isoforms translocated to the membrane compartment, while delta, epsilon, zeta and theta; maintained their initial subcellular distribution. Twenty-four hours after glutamate treatment, the total protein kinase C labelling had increased, particularly the epsilon isoform, which accounted for 34% of the total densitometric signal. At this time, protein kinase C beta1, delta, epsilon and zeta isoforms were mainly detected in the membrane compartment, while gamma and theta; signals were displayed almost solely in the cytosol. Basal intracellular calcium concentration (FURA 2 assay) was concentration-dependently increased (maximum effect +77%) 30 min, but not 24h after a 10 min glutamate (10-100 microM) treatment, while the net increase induced by electrical stimulation (10 Hz, 10s) was consistently reduced (maximum effect -64%). The N-methyl-d-aspartate receptor antagonist, MK-801, 1 microM, prevented glutamate action both 30 min and 24 h after treatment, while non-selective protein kinase C inhibitors, ineffective at 30 min, potentiated it at 24 h. These findings show that protein kinase C isoforms are differently activated and involved in the early and delayed glutamate actions, and that the prevailing effect of their activation is neuroprotective. 相似文献
140.
Manera C Betti L Cavallini T Giannaccini G Martinelli A Ortore G Saccomanni G Trincavelli L Tuccinardi T Ferrarini PL 《Bioorganic & medicinal chemistry letters》2005,15(20):4604-4610
A series of 1,8-naphthyridine derivatives bearing various substituents in position 3, 4, and 7 of the heterocyclic nucleus have been synthesized and evaluated for their affinity at the bovine and human adenosine receptors. The new compounds were found to lack the affinity toward A(1)AR, whereas many of them are able to acquire an interesting affinity and selectivity for the A(2A)AR. 相似文献