88 resultados para 8257
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"March 1967."
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Includes index.
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In this work, pyrolysis-molecular beam mass spectrometry analysis coupled with principal components analysis and (13)C-labeled tetramethylammonium hydroxide thermochemolysis were used to study lignin oxidation, depolymerization, and demethylation of spruce wood treated by biomimetic oxidative systems. Neat Fenton and chelator-mediated Fenton reaction (CMFR) systems as well as cellulosic enzyme treatments were used to mimic the nonenzymatic process involved in wood brown-rot biodegradation. The results suggest that compared with enzymatic processes, Fenton-based treatment more readily opens the structure of the lignocellulosic matrix, freeing cellulose fibrils from the matrix. The results demonstrate that, under the current treatment conditions, Fenton and CMFR treatment cause limited demethoxylation of lignin in the insoluble wood residue. However, analysis of a water-extractable fraction revealed considerable soluble lignin residue structures that had undergone side chain oxidation as well as demethoxylation upon CMFR treatment. This research has implications for our understanding of nonenzymatic degradation of wood and the diffusion of CMFR agents in the wood cell wall during fungal degradation processes.
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The very high antiproliferative activity of [Co(Cl)(H2O)(phendione)(2)][BF4] (phendione is 1,10-phenanthroline-5,6-dione) against three human tumor cell lines (half-maximal inhibitory concentration below 1 mu M) and its slight selectivity for the colorectal tumor cell line compared with healthy human fibroblasts led us to explore the mechanisms of action underlying this promising antitumor potential. As previously shown by our group, this complex induces cell cycle arrest in S phase and subsequent cell death by apoptosis and it also reduces the expression of proteins typically upregulated in tumors. In the present work, we demonstrate that [Co(Cl)(phendione)(2)(H2O)][BF4] (1) does not reduce the viability of nontumorigenic breast epithelial cells by more than 85 % at 1 mu M, (2) promotes the upregulation of proapoptotic Bax and cell-cycle-related p21, and (3) induces release of lactate dehydrogenase, which is partially reversed by ursodeoxycholic acid. DNA interaction studies were performed to uncover the genotoxicity of the complex and demonstrate that even though it displays K (b) (+/- A standard error of the mean) of (3.48 +/- A 0.03) x 10(5) M-1 and is able to produce double-strand breaks in a concentration-dependent manner, it does not exert any clastogenic effect ex vivo, ruling out DNA as a major cellular target for the complex. Steady-state and time-resolved fluorescence spectroscopy studies are indicative of a strong and specific interaction of the complex with human serum albumin, involving one binding site, at a distance of approximately 1.5 nm for the Trp214 indole side chain with log K (b) similar to 4.7, thus suggesting that this complex can be efficiently transported by albumin in the blood plasma.
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Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica
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J Biol Inorg Chem (2011) 16:1241–1254 DOI 10.1007/s00775-011-0812-9
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J Biol Inorg Chem (2008) 13:1185–1195 DOI 10.1007/s00775-008-0414-3
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J Biol Inorg Chem (2008) 13:1321–1333 DOI 10.1007/s00775-008-0416-1
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J Biol Inorg Chem. 2008 Jun;13(5):779-87. doi: 10.1007/s00775-008-0365-8
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J Biol Inorg Chem. 2008 Jun;13(5):737-53. doi: 10.1007/s00775-008-0359-6
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J Biol Inorg Chem (2007) 12:777–787 DOI 10.1007/s00775-007-0229-7
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J Biol Inorg Chem (2007) 12:691–698 DOI 10.1007/s00775-007-0219-9
Correlating EPR and X-ray structural analysis of arsenite-inhibited forms of aldehyde oxidoreductase
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J Biol Inorg Chem (2007) 12:353–366 DOI 10.1007/s00775-006-0191-9
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J Biol Inorg Chem (2006) 11: 609–616 DOI 10.1007/s00775-006-0110-0
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J Biol Inorg Chem (2006) 11: 548–558 DOI 10.1007/s00775-006-0104-y