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排序方式: 共有302条查询结果,搜索用时 15 毫秒
71.
Lu X Zhang N Vasquez K Barton M Legerski R 《Biochemical and biophysical research communications》2005,336(1):69-75
The recognition and removal of interstrand cross-links is perhaps the least understood of all repair pathways in eukaryotic cells. We have shown previously that uncoupling of cross-links occurs in mammalian cell extracts and have identified a number of factors that mediate this process. However, we have not observed complete repair of the substrate in this system. Here, we show that uncoupling of interstrand cross-links also occurs in Xenopus laevis egg extracts, and that the initial products of this reaction are identical to the products observed in mammalian cell extracts suggesting a common mechanism. However in contrast to mammalian cell extracts, we observe repair of the cross-linked substrate in the Xenopus extracts presumably by a translesion bypass mechanism that allows replication past the uncoupled monoadduct, and its likely subsequent removal by nucleotide excision repair. This repair process is shown to be highly mutagenic consistent with bypass synthesis. 相似文献
72.
Human high mobility group box (HMGB) 1 and -2 proteins are highly conserved and abundant chromosomal proteins that regulate chromatin structure and DNA metabolism. HMGB proteins bind preferentially to DNA that is bent or underwound and to DNA damaged by agents such as cisplatin, UVC radiation, and benzo[a]pyrenediol epoxide (BPDE). Binding of HMGB1 to DNA adducts is thought to inhibit nucleotide excision repair (NER), leading to cell death, but the biological roles of these proteins remain obscure. We have used psoralen-modified triplex-forming oligonucleotides (TFOs) to direct a psoralen-DNA interstrand cross-link (ICL) to a specific site to determine the effect of HMGB proteins on recognition of these lesions. Our results reveal that human HMGB1 (but not HMGB2) binds with high affinity and specificity to psoralen ICLs, and interacts with the essential NER protein, replication protein A (RPA), at these lesions. RPA, shown previously to bind tightly to these lesions, also binds in the presence of HMGB1, without displacing HMGB1. A discrete ternary complex is formed, containing HMGB1, RPA, and psoralen-damaged DNA. Thus, HMGB1 has the ability to recognize ICLs, can cooperate with RPA in doing so, and likely modulates their repair by the NER machinery. The abundance of HMGB1 suggests that it may play an important role in determining the sensitivity of cells to DNA damage under physiological, experimental, and therapeutic conditions. 相似文献
73.
Adoptively transferred resistance to Schistosoma mansoni in the snail intermediate host Biomphalaria glabrata was measured as a function of miracidial challenge dose. Schistosome-susceptible snails implanted with the amebocyte-producing organ (APO) from resistant donors showed 29 and 39% prevalences of infection after challenge with 5 and 10 miracidia, respectively, but 68-83% prevalences when exposed to 25-200 miracidia. Prevalences in control (untampered) susceptible snails ranged from 97 to 100% at the different miracidial doses. Higher infection prevalences at elevated doses suggest that a range of transferred resistance occurs and possibly that low levels of APO-derived plasma factors or hemocytes in some recipients can be overwhelmed by larger numbers of parasites. 相似文献
74.
R B Messing B J Vasquez V R Spiehler J L Martinez R A Jensen H Rigter J L McGaugh 《Life sciences》1980,26(12):921-927
Opiate receptor-ligand binding was investigated in brains of young and aged female F344 rats. A significant reduction in the density of binding sites for 3H-dihydromorphine was observed in the thalamus and midbrain of aged rats. Evidence of two binding sites was observed in the anterior cortex of young rats, whereas aged rats exhibited only a single site. The occurrence of pituitary tumors in the old female rats did not affect 3H-dihydromorphine binding. The highest density of dihydromorphine binding sites was found in the diencephalon, and the lowest density in the hippocampus. Receptor densities in the anterior cortex, striatum, amygdala, frontal poles and midbrain were intermediate, and few, if any, high affinity binding sites for dihydromorphine were found in the pons-medulla or posterior cortex. 相似文献
75.
Abandoning ineffective medical practices and mitigating the risks of untested practices are important for improving patient health and containing healthcare costs. Historically, this process has relied on the evidence base, societal values, cultural tensions, and political sway, but not necessarily in that order. We propose a conceptual framework to guide and prioritize this process, shifting emphasis toward the principles of evidence-based medicine, acknowledging that evidence may still be misinterpreted or distorted by recalcitrant proponents of entrenched practices and other biases. 相似文献
76.
Muthiah Manoharan Thazha P. Prakash Isabelle Barber-peoc'h Balkrishen Bhat Guillermo Vasquez Bruce S. Ross 《Nucleosides, nucleotides & nucleic acids》2013,32(6-7):1199-1201
Abstract A new protecting group, 2-cyanoethyloxycarbonyl, or CEOC, has been developed for amino groups and utilized in synthesizing modified oligonucleotides. (CEOC)-oxy-succinimide reagent has been synthesized to introduce this protecting group. The protecting group is removed by standard oligonucleotide deprotection protocols. Using this approach, oligonucleotides have been synthesized with various types of alkylamine substituents. 相似文献
77.
Yucai Wang Justin W. Leung Yingjun Jiang Megan G. Lowery Huong Do Karen M. Vasquez Junjie Chen Weidong Wang Lei Li 《Molecular cell》2013,49(5):997-1009
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78.
Julian Vasquez Heilig Heather Cole Angélica Aguilar 《Arts Education Policy Review》2013,114(4):136-161
This historical narrative tracks the evolution and devolution of visual arts education from Dewey's progressive era pedagogy and the theory of the arts as experience through the modern accountability movement. Archival material, state curricular documents, and conversations with policymakers show an increasing focus on core subject areas of reading, writing, and mathematics at the expense of arts education. Texas House Bill 3, the third generation of accountability legislation in the Lone Star State, provides a case study of the status of arts education after more than fifteen years of high-stakes testing and accountability. Policy considerations are offered for arts education and its future standing within the public educational curriculum. 相似文献
79.
Elisabeth APM Romme David A McAllister John T Murchison Edwin JR Van Beek George S Petrides Cameron OS Price Erica PA Rutten Frank WJM Smeenk Emiel FM Wouters William MacNee 《Respiratory research》2013,14(1):129