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951.
Mira L Silva M Rocha R Manso CF 《Redox report : communications in free radical research》1999,4(1-2):69-74
The relative activities of some hydrogen-donating antioxidants were assessed by comparing their activities with that of Trolox (Trolox equivalent antioxidant capacity, TEAC) for scavenging the ABTS radical cation (ABTS.+) generated in the aqueous phase. We have verified, however, that TEAC values may change with the concentration of compounds and with the measuring times used. Not withstanding, TEAC values do not differ significantly if the compounds have kinetic curves of ABTS.+ formation similar to that of Trolox. This is the case with ascorbic acid, whose TEAC values, determined by using five concentrations at three different measuring times, are very close. For the flavonoids studied (catechin, rutin, naringenin and silibinin) which have kinetic curves of ABTS.+ formation different from that of Trolox, the TEAC values decrease with increasing concentrations of the compounds for each measuring time, and increase with increasing measuring times for each concentration. In the present study, we conclude that, in order to evaluate relative antioxidant activities of compounds by the ABTS assay, it is essential to perform kinetic studies to assess scavenging of ABTS.+ by these compounds. Therefore, when the TEAC values of compounds are determined for more than one measuring time, we may be sure that all the antioxidant potential of compounds is being considered and whether or not it is possible to establish a hierarchy for their antioxidant activities. 相似文献
952.
Balagopalan L Barr VA Sommers CL Barda-Saad M Goyal A Isakowitz MS Samelson LE 《Molecular and cellular biology》2007,27(24):8622-8636
The engagement of the T-cell receptor (TCR) causes the rapid recruitment of multiple signaling molecules into clusters with the TCR. Upon receptor activation, the adapters LAT and SLP-76, visualized as chimeric proteins tagged with yellow fluorescent protein, transiently associate with and then rapidly dissociate from the TCR. Previously, we demonstrated that after recruitment into signaling clusters, SLP-76 is endocytosed in vesicles via a lipid raft-dependent pathway that requires the interaction of the endocytic machinery with ubiquitylated proteins. In this study, we focus on LAT and demonstrate that signaling clusters containing this adapter are internalized into distinct intracellular compartments and dissipate rapidly upon TCR activation. The internalization of LAT was inhibited in cells expressing versions of the ubiquitin ligase c-Cbl mutated in the RING domain and in T cells from mice lacking c-Cbl. Moreover, c-Cbl RING mutant forms suppressed LAT ubiquitylation and caused an increase in cellular LAT levels, as well as basal and TCR-induced levels of phosphorylated LAT. Collectively, these data indicate that following the rapid formation of signaling complexes upon TCR stimulation, c-Cbl activity is involved in the internalization and possible downregulation of a subset of activated signaling molecules. 相似文献
953.
Minkova K Tchorbadjieva M Tchernov A Stojanova M Gigova L Busheva M 《Biotechnology letters》2007,29(4):647-651
A rapid, inexpensive and reliable procedure for separation and purification of C-phycocyanin (C-PC) and allophycocyanin (APC)
from Arthronema africanum based on a previously described rivanol-sulfate method for C-PC purification was developed. Exclusion of NaCl from the extraction
buffer resulted in complete separation of APC and C-PC, two-fold reduction of rivanol treatments, and a higher yield and purity
of C-PC. Pure C-PC (A620/A280 of 4.52) and APC (A652/A280 of 2.41) were obtained. The estimated molecular masses of the α and β subunits were 17 and 19 kDа for С-phycocyanin and 16
and 18 kDа for APC, respectively. The overall C-PC recovery of 55% (w/w) from its content (100 mg) in the crude extract was
10–20% higher than so far reported. The procedure appears promising for scaling up and broader applications. 相似文献
954.
The location and penetration patterns of two fluorescently labelled, surface active molecules into normal and waxy wheat starch granules prior, during and after the temperature-induced gelatinization were studied by means of confocal laser scanning microscopy (CLSM). Amphiphilic dyes were found to have a tendency to penetrate wheat starch granules in aqueous suspension. The penetration patterns were however found to be dependent on the contact time, type of starch and the chain length (C12 vs. C16) of the amphiphilic dye. The penetration of amphiphilic dyes through the starch granule matrix proved to be less restricted in waxy than in normal wheat starch. For a given type of starch, the penetration of the longer chain dye was more constrained than that of the shorter chain one. The extent to which the dye diffuses into the granule matrix as it gelatinizes is also affected by the chain length of the dye, diffusion of the shorter chain dye occurring more profusely and at lower temperatures than for the longer chain one. These differences are suggested to be related to the dissociation temperature of the AM-amphiphilic dye complexes. 相似文献
955.
Dal Piaz F Nigro P Braca A De Tommasi N Belisario MA 《Free radical biology & medicine》2007,43(10):1409-1422
13-Hydroxy-15-oxo-zoapatlin (OZ), a nor-kaurane diterpene, was first described as a compound inhibiting the proliferation of human cancer cell lines. Successively, it was reported that OZ inhibits the G2 DNA damage checkpoint and causes mitotic arrest. To get more insight into the molecular mechanism(s) underlying the antitumor potential of OZ, we evaluated the proapoptotic activity of this molecule. OZ was found to induce hypodiploidia and phosphatidylserine externalization, two hallmarks of apoptosis; to disrupt mitochondrial membrane potential; and to trigger caspase-3 activation. OZ-induced cell death, mostly dependent upon the presence of the alpha,beta-carbonyl group, is strongly related to alterations in the cellular redox balance. The interaction of OZ with cellular components and proteins containing reactive thiols was evaluated by mass spectrometry-based approaches. A specific reactivity of this compound toward glutathione and thioredoxin was observed. 相似文献
956.
Crystallization and preliminary X-ray diffraction analysis of PD-L1, a highly glycosylated ribosome inactivating protein with DNase activity 总被引:1,自引:0,他引:1
Ruggiero A Chambery A Di Maro A Mastroianni A Parente A Berisio R 《Protein and peptide letters》2007,14(4):407-409
PD-L1 is a highly glycosylated type 1 ribosome inactivating protein, from Phytolacca dioica leaves, with the peculiarity to act also as a DNase. PD-L1 has been successfully crystallized using vapour diffusion and seeding techniques. Crystals belong to the monoclinic C2 space group, with unit cell dimensions a=161.01, b=34.73, c=120.63 A, beta=127.99 degrees . Two molecules are present in the asymmetric unit. Phase determination has been achieved using molecular replacement. 相似文献
957.
958.
959.
Georges Raad Mira Hazzouri Silvia Bottini Michele Trabucchi Joseph Azoury Valérie Grandjean 《Andrologie》2017,27(1):20
There is substantial evidence that paternal obesity is associated not only with an increased incidence of infertility, but also with an increased risk of metabolic disturbance in adult offspring. Apparently, several mechanisms may contribute to the sperm quality alterations associated with paternal obesity, such as physiological/hormonal alterations, oxidative stress, and epigenetic alterations. Along these lines, modifications of hormonal profiles namely reduced androgen levels and elevated estrogen levels, were found associated with lower sperm concentration and seminal volume. Additionally, oxidative stress in testis may induce an increase of the percentage of sperm with DNA fragmentation. The latter, relate to other peculiarities such as alteration of the embryonic development, increased risk of miscarriage, and development of chronic morbidity in the offspring, including childhood cancers. Undoubtedly, epigenetic alterations (ie, DNA methylation, chromatin modifications, and small RNA deregulation) of sperm related to paternal obesity and their consequences on the progeny are poorly understood determinants of paternal obesity-induced transmission. In this review, we summarize and discuss the data available in the literature regarding the biological, physiological, and molecular consequences of paternal obesity on male fertility potential and ultimately progeny health. 相似文献
960.
Óscar Mira Cristina B. Sánchez-Prieto Deborah A. Dawson Terry Burke Alberto Tinaut Juan G. Martínez 《Conservation Genetics》2017,18(4):837-851
Population persistence depends in many cases on gene flow between local populations. Parnassius apollo nevadensis is an endemic subspecies of Apollo butterfly in the Sierra Nevada (southern Spain), whose populations are distributed in discrete patches at altitudes between 1850 and 2700 m. In this paper, we use 13 microsatellite loci to examine the genetic structure of this P. apollo subspecies. We revealed both a strong pattern of isolation by distance (which was stronger when calculated with realistic travel distances that accounted for topography) and source–sink dynamics. The observed population genetic structure is consistent with strongly asymmetrical gene flow, leading to constant directional migration and differential connectivity among the populations. The apparently contradictory results from the clustering algorithms (Structure and Geneland) are also consistent with a recent (<100 ya) reduction in the distribution range. The results point to global warming as a possible cause of this reduction, as in other populations of this species. We identify some natural and anthropogenic barriers to gene flow that may be the cause of the recent population structure and source–sink dynamics. 相似文献