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排序方式: 共有204条查询结果,搜索用时 15 毫秒
101.
Braunstein GM Roman RM Clancy JP Kudlow BA Taylor AL Shylonsky VG Jovov B Peter K Jilling T Ismailov II Benos DJ Schwiebert LM Fitz JG Schwiebert EM 《The Journal of biological chemistry》2001,276(9):6621-6630
These studies provide evidence that cystic fibrosis transmembrane conductance regulator (CFTR) potentiates and accelerates regulatory volume decrease (RVD) following hypotonic challenge by an autocrine mechanism involving ATP release and signaling. In wild-type CFTR-expressing cells, CFTR augments constitutive ATP release and enhances ATP release stimulated by hypotonic challenge. CFTR itself does not appear to conduct ATP. Instead, ATP is released by a separate channel, whose activity is potentiated by CFTR. Blockade of ATP release by ion channel blocking drugs, gadolinium chloride (Gd(3+)) and 4,4'-diisothiocyanatostilbene-2,2'disulfonic acid (DIDS), attenuated the effects of CFTR on acceleration and potentiation of RVD. These results support a key role for extracellular ATP and autocrine and paracrine purinergic signaling in the regulation of membrane ion permeability and suggest that CFTR potentiates ATP release by stimulating a separate ATP channel to strengthen autocrine control of cell volume regulation. 相似文献
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103.
Importance of glucose-6-phosphate dehydrogenase activity in cell death 总被引:12,自引:0,他引:12
Tian Wang-Ni; Braunstein Leigh D.; Apse Kira; Pang Jiongdong; Rose Mark; Tian Xiaoni; Stanton Robert C. 《American journal of physiology. Cell physiology》1999,276(5):C1121
The intracellular redox potential plays an important role incell survival. The principal intracellular reductant NADPH is mainlyproduced by the pentose phosphate pathway by glucose-6-phosphate dehydrogenase (G6PDH), the rate-limiting enzyme, and by6-phosphogluconate dehydrogenase. Considering the importance of NADPH,we hypothesized that G6PDH plays a critical role in cell death. Ourresults show that 1) G6PDHinhibitors potentiatedH2O2-inducedcell death; 2) overexpression ofG6PDH increased resistance toH2O2-induced cell death; 3) serum deprivation, astimulator of cell death, was associated with decreased G6PDH activityand resulted in elevated reactive oxygen species (ROS);4) additions of substrates for G6PDHto serum-deprived cells almost completely abrogated the serumdeprivation-induced rise in ROS; 5)consequences of G6PDH inhibition included a significant increase inapoptosis, loss of protein thiols, and degradation of G6PDH; and6) G6PDH inhibition caused changesin mitogen-activated protein kinase phosphorylation that were similarto the changes seen withH2O2.We conclude that G6PDH plays a critical role in cell death by affectingthe redox potential. 相似文献
104.
Cross validation (CV) was used to analyze the effects of different environments and different genotypic samples on estimates of the proportion of genotypic variance explained by QTL (p). Testcrosses of 344 F(3) maize lines grown in four environments were evaluated for a number of agronomic traits. In each of 200 replicated CV runs, this data set was subdivided into an estimation set (ES) and various test sets (TS). ES were used to map QTL and estimate p for each run (p(ES)) and its median (p(ES)) across all runs. The bias of these estimates was assessed by comparison with the median (p(TS.ES)) obtained from TS. We also used two independent validation samples derived from the same cross for further comparison. The median p(ES) showed a large upward bias compared to p(TS.ES). Environmental sampling generally had a smaller effect on the bias of p(ES) than genotypic sampling or both factors simultaneously. In independent validation, p(TS.ES) was on average only 50% of p(ES). A wide range among p(ES) reflected a large sampling error of these estimates. QTL frequency distributions and comparison of estimated QTL effects indicated a low precision of QTL localization and an upward bias in the absolute values of estimated QTL effects from ES. CV with data from three QTL studies reported in the literature yielded similar results as those obtained with maize testcrosses. We therefore recommend CV for obtaining asymptotically unbiased estimates of p and consequently a realistic assessment of the prospects of MAS. 相似文献
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107.
Fabrizio Altarelli Alfredo Braunstein Luca Dall’Asta Caterina De Bacco Silvio Franz 《PloS one》2015,10(12)
We present a message-passing algorithm to solve a series of edge-disjoint path problems on graphs based on the zero-temperature cavity equations. Edge-disjoint paths problems are important in the general context of routing, that can be defined by incorporating under a unique framework both traffic optimization and total path length minimization. The computation of the cavity equations can be performed efficiently by exploiting a mapping of a generalized edge-disjoint path problem on a star graph onto a weighted maximum matching problem. We perform extensive numerical simulations on random graphs of various types to test the performance both in terms of path length minimization and maximization of the number of accommodated paths. In addition, we test the performance on benchmark instances on various graphs by comparison with state-of-the-art algorithms and results found in the literature. Our message-passing algorithm always outperforms the others in terms of the number of accommodated paths when considering non trivial instances (otherwise it gives the same trivial results). Remarkably, the largest improvement in performance with respect to the other methods employed is found in the case of benchmarks with meshes, where the validity hypothesis behind message-passing is expected to worsen. In these cases, even though the exact message-passing equations do not converge, by introducing a reinforcement parameter to force convergence towards a sub optimal solution, we were able to always outperform the other algorithms with a peak of 27% performance improvement in terms of accommodated paths. On random graphs, we numerically observe two separated regimes: one in which all paths can be accommodated and one in which this is not possible. We also investigate the behavior of both the number of paths to be accommodated and their minimum total length. 相似文献
108.
Structure of the retinal determination protein Dachshund reveals a DNA binding motif 总被引:1,自引:0,他引:1
Kim SS Zhang RG Braunstein SE Joachimiak A Cvekl A Hegde RS 《Structure (London, England : 1993)》2002,10(6):787-795
The Dachshund proteins are essential components of a regulatory network controlling cell fate determination. They have been implicated in eye, limb, brain, and muscle development. These proteins cannot be assigned to any recognizable structural or functional class based on amino acid sequence analysis. The 1.65 A crystal structure of the most conserved domain of human DACHSHUND is reported here. The protein forms an alpha/beta structure containing a DNA binding motif similar to that found in the winged helix/forkhead subgroup of the helix-turn-helix family. This unexpected finding alters the previously proposed molecular models for the role of Dachshund in the eye determination pathway. Furthermore, it provides a rational framework for future mechanistic analyses of the Dachshund proteins in several developmental contexts. 相似文献
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110.
Pierre D. Harvey Karine Hierso Pierre Braunstein Xavier Morise 《Inorganica chimica acta》1996,250(1-2):337-343
The trinuclear clusters [Pd3(μ-dppm)3(CO)]2+ and [PtPdCo(μ-dppm)2(CO)3(CNtBu)]+ exhibit a large and a small cavity, respectively, formed by the phenyl rings of the bridging diphosphine ligands. Their binding constants (K11) with halide ions (X−) were obtained by UV-Vis spectroscopy. The binding ability varies as I− > Br− > Cl−, and [Pd3(μ-dppm)3(CO)]2+ > [ptPdCo(μ-dppm)2-(CO)3(CNtBu)]+. The MO diagram for the related cluster [Pd2Co(μ-dppm)2(CO)4]+ has been addressed theoretically in order to predict the nature of the lowest energy electronic bands. For this class of compounds, the lowest energy bands are assigned to charge transfers from the Co center to the Pd2 centers. 相似文献