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481.
Both numerical and experimental studies have been performed to characterize the fluid flow inside the lateral aneurysms arising from the curved parent vessels at various angles gamma. The implicit solver was based on the time-dependent Navier-Stokes equations of incompressible laminar flow. Solutions were generated by a cell-center finite-volume method that used second order upwind and second order center flux difference splitting for the convection and diffusion term, respectively. The second order Crank-Nicolson method was used in the time integration term while the SIMPLEC algorithm was adopted to handle the pressure-velocity coupling. Complementarily, the particle tracking velocimetry (PTV) was used to measure the velocity fields. The conditions selected were to simulate an internal carotid artery with a diameter of 5 mm by similarity rules. The values of gamma explored were 0 degrees, 45 degrees, 90 degrees, and 135 degrees. Pulsatile flow with Wormersley number 3.9 and Reynolds numbers varying from 350 to 850 was considered. The computed results are firstly verified by the PTV measured ones. Discussion of the results is in terms of pulsatile main and secondary velocity vector fields, inflow rates into the aneurysm, and the distributions of wall shear stress and static pressure. It is found that among the angles examined gamma=45( composite function) is the riskiest angle from a fluid dynamics point of view and the aneurysmal dome is at risk. 相似文献
482.
Chih‐Yang Huang Yi‐Fan Liou Shu‐Ying Chung Pei‐Ying Pai Chung‐Ben Kan Chia‐Hua Kuo Chang‐Hai Tsai Fuu‐Jen Tsai Jia‐Long Chen Jing‐Ying Lin 《Cell biochemistry and function》2010,28(4):313-320
Glucose is the primary energy substrate for neurons. Glucose transporter 3 (Glut3) localizes at the neuronal cellular membrane, which transports glucose from the extracelluar space into neurons. Ischemia results in an increased energy demand that is associated with profound changes in brain energy metabolism. Magnesium sulfate (MgSO4) ameliorates ischemia‐induced neuronal death in the rat and gerbil model. We investigated the effects of MgSO4 administration on the expression of Glut3 in cortex and hippocampus of gerbils during ischemia. The focal cerebral ischemia was produced by unilateral occlusion of the right common carotid artery and right middle cerebral artery. Following ischemia, Glut3 expression increased significantly versus non‐ischemic (contra‐lateral) cortex and hippocampus. MgSO4 treatment significantly increased the level of Glut3 expression in the non‐ischemic and ischemic cortex and hippocampus. We found that the MgSO4‐induced increase in Glut3 expression was not reversed by administration of U0126, a MEK kinase inhibitor. These results suggest that other factors may function to modulate the MgSO4‐induced Glut3 response. In all, our data showed that MgSO4 increases the expression of Glut3 in the cortex and hippocampus of gerbil brains both in non‐ischemia and ischemia status. However, the MEK signaling pathway might not be involved in MgSO4‐induced Glut3 expression following focal ischemia. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
483.
A chitinase (CHT), a chitosanase (CHS) and a protease (PRO) were purified from the culture supernatant of Serratia sp. TKU020 with squid pen as the sole carbon/nitrogen source. The molecular masses of CHT, CHS and PRO determined by SDS-PAGE were approximately 65 kDa, 55 kDa and 55 kDa, respectively. CHT and CHS were inhibited by Mn2+, EDTA and PRO was inhibited by Mg2+, EDTA. The antioxidant activity of TKU020 culture supernatant was 78% (DPPH scavenging ability). N-Acetylglucosamine (GlcNAc) and N-acetyl chitobiose (GlcNAc)2 were also produced from the culture supernatant by using TKU020 strain fermentation. The maximum production of GlcNAc and (GlcNAc)2 was 1.3 mg/mL and 2.7 mg/mL, respectively, after 4 days of fermentation. With this method, we have shown that squid pen wastes can be utilized and it is effective in the production of enzymes, antioxidants, and N-acetyl chitooligosaccharides, facilitating its potential use in industrial applications and functional foods. 相似文献
484.
Yung-Hun Yang Young-Bok Kang Dae-Hee Kim Tek-Hyung Lee Sung-Hee Park Kwangwon Lee Dongwon Yoo Kwang-kyung Liou Hee-Chan Lee Jae-Kyung Sohng Byung-Gee Kim 《Journal of Molecular Catalysis .B, Enzymatic》2010,62(3-4):282-287
Production of deoxy-thymidine-diphosphate (TDP)-sugars as substrates of glycosyltransferases, has been one of main hurdles for combinatorial antibiotic biosynthesis, which combines sugar moiety with aglycon of various antibiotics. Here, we report the one-pot enzymatic synthesis of TDP-2-deoxy-glucose employing high efficient TMP kinase (TMK; E.C. 2.7.2.12), acetate kinase (ACK; E.C. 2.7.1.21), and TDP-glucose synthase (TGS; E.C. 2.7.7.24) with phosphomannomutase (PMM; E.C. 5.4.2.8). In this study, replacing phosphoglucomutase (PGM; E.C. 5.4.2) by PMM from Escherichia coli gave four times higher specific activity on 2-deoxy-6-phosphate glucose, suggesting that the activity on 2-deoxy-glucose-6-phosphate was mainly affected by PMM activity, not PGM activity. Using an in vitro system starting from TMP and 2-deoxy-glucose-6-phosphate glucose, TDP-2-deoxy-glucose (63% yield) was successfully synthesized. Considering low productivity of NDP-sugars from cheap starting materials, this paper showed how production of NDP-sugars could be enhanced by controlling mutase activity. 相似文献
485.
Tzu-Ching Chang Yen-Chung Chen Ming-Hua Yang Chien-Hung Chen En-Wei Hsing Bor-Sheng Ko Jun-Yang Liou Kenneth K. Wu 《PloS one》2010,5(2)
Background
Rho kinases (ROCKs) mediate cell contraction, local adhesion, and cell motility, which are considered to be important in cell differentiation. We postulated that ROCKs are involved in controlling embryonic stem (ES) cell renewal and differentiation.Methodology/Principal Findings
CCE, a murine ES cell, was treated with Y-27632 for 48 to 96 hours and colony formation was evaluated. Y-27632 blocked CCE colony formation and induced CCE to grow as individual cells, regardless of the initial seeding cell density either at 104/cm2 (“high” seeding density) or 2×103/cm2 (“low” density). However, at high seeding density, Y-27632–treated cells exhibited reduction of alkaline phosphatase (AP) staining and Oct3/4 expression. They expressed SOX-1, nestin, and MAP2c, but not βIII-tubulin or NG-2. They did not express endoderm or mesoderm lineage markers. After removal of Y-27632, the cells failed to form colonies or regain undifferentiated state. Silencing of ROCK-1 or ROCK-2 with selective small interference RNA induced CCE morphological changes similar to Y-27632. Silencing of ROCK-1 or ROCK-2 individually was sufficient to cause reduction of AP and Oct3/4, and expression of SOX-1, nestin, and MAP2c; and combined silencing of both ROCKs did not augment the effects exerted by individual ROCK siRNA. Y-27632–treated CCE cells seeded at 2×103 or 6.6×103 cells/cm2 did not lose renewal factors or express differentiation markers. Furthermore, they were able to form AP-positive colonies after removal of Y-27632 and reseeding. Similar to ROCK inhibition by Y-27632, silencing of ROCK-1 or ROCK-2 in cells seeded at 2×103/cm2 did not change renewal factors.Conclusions/Significance
We conclude that ROCKs promote ES cell colony formation, maintain them at undifferentiated state, and prevent them from neural differentiation at high seeding density. ROCK inhibition represents a new strategy for preparing large numbers of neural progenitor cells. 相似文献486.
HIV-1 infection and regulation of Tat function in macrophages 总被引:1,自引:0,他引:1
Liou LY Herrmann CH Rice AP 《The international journal of biochemistry & cell biology》2004,36(9):1767-1775
487.
Vu CB Luke GP Kawahata N Shakespeare WC Wang Y Sundaramoorthi R Metcalf CA Keenan TP Pradeepan S Corpuz E Merry T Bohacek RS Dalgarno DC Narula SS van Schravendijk MR Ram MK Adams S Liou S Keats JA Violette SM Guan W Weigele M Sawyer TK 《Bioorganic & medicinal chemistry letters》2003,13(18):3071-3074
The design of bone-targeted pyrido[2,3-d]pyrimidin-7-ones as Src tyrosine kinase inhibitors is described. Leveraging SAR from known compounds and using structure-based methods, we were able to rapidly incorporate bone binding components, which maintained, and even increased potency against the target enzyme. Compound 4 displayed a high affinity for hydroxyapatite, a major constituent of bone, and demonstrated antiresoprtive activity in our cell-based assay. 相似文献
488.
Two genes, pbpA (orf18) and pbp2 (orf19) located on the downstream of clavulanic acid (CA) gene cluster of Streptomyces clavuligerus were cloned into pET-28a(+), and confirmed to encode a family of high molecular-weight penicillin-binding proteins (PBPs).
Both genes were amplified from genomic DNA by PCR and expressed in E. coli BL21 (DE3). Hydropathy plots of the proteins revealed a single stretch of hydrophobic amino acids indicating them to be transmembrane
proteins. Pbp2 had lower affinity to penicillin G compared to PbpA, and was essential to the cell growth in contrast to PbpA.
Revisions requested 3 November 2005; Revisions received 13 December 2005 相似文献
489.
Isolation, chemical structure, acute toxicity, and some physicochemical properties of territrem C from Aspergillus terreus. 总被引:4,自引:0,他引:4 下载免费PDF全文
Territrem C, a new tremorgenic mycotoxin (C28H32O9; molecular weight, 512.20) was isolated from the chloroform extract of rice cultures of Aspergillus terreus 23-1, which also produces territrems A and B. Isolation, acute toxicity, and some physicochemical properties of territrem C are discussed in this paper. The spectral and chemical evidence indicated that the structural difference between territrem C and territrem B (C29H34O9) was in their phenyl moieties: a 4-hydroxy-3,5-dimethoxy phenyl group in territrem C and a 3,4,5-trimethoxy phenyl group in territrem B. It was also demonstrated that territrem B was obtained by methylation of territrem C with dimethyl sulfate. 相似文献
490.
An approximate method for solving the nonlinear diffusion problem in the case of a power-function variation of the diffusion coefficient with concentration has been applied to a drying process with simultaneous enzyme inactivation. Experimental results obtained by air drying of soybean lipoxygenase entrapped in a glucose calcium-alginate gel are in good agreement with the predicted behavior, whereas hardly any differences occur between the results obtained with the approximate method and those obtained by a numerical solution of the original model. 相似文献