排序方式: 共有49条查询结果,搜索用时 15 毫秒
1.
Zarifi Masri Arvydas Ruseckas Evguenia V. Emelianova Linjun Wang Ashu K. Bansal Andrew Matheson Henrik T. Lemke Martin M. Nielsen Ha Nguyen Olivier Coulembier Philippe Dubois David Beljonne Ifor D. W. Samuel 《Liver Transplantation》2013,3(11):1445-1453
A joint experimental and theoretical study of singlet exciton diffusion in spin‐coated poly(3‐hexylthiophene) (P3HT) films and its dependence on molecular weight is presented. The results show that exciton diffusion is fast along the co‐facial π–π aggregates of polymer chromophores and about 100 times slower in the lateral direction between aggregates. Exciton hopping between aggregates is found to show a subtle dependence on interchain coupling, aggregate size, and Boltzmann statistics. Additionally, a clear correlation is observed between the effective exciton diffusion coefficient, the degree of aggregation of chromophores, and exciton delocalization along the polymer chain, which suggests that exciton diffusion length can be enhanced by tailored synthesis and processing conditions. 相似文献
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Evguenia Krastinova Remonie Seng Patrick Yeni Jean-Paul Viard Daniel Vittecoq Caroline Lascoux-Combe Erwan Fourn Golriz Pahlavan Jean Fran?ois Delfraissy Laurence Meyer for the ANRS PRIMO COPANA Cohorts 《PloS one》2013,8(8)
Objective
Guidelines for initiating HIV treatment are regularly revised. We explored how physicians in France have applied these evolving guidelines for ART initiation over the last decade in two different situations: chronic (CHI) and primary HIV-1 infection (PHI), since specific recommendations for PHI are also provided in France.Methods
Data came from the ANRS PRIMO (1267 patients enrolled during PHI in 1996–2010) and COPANA (800 subjects enrolled at HIV diagnosis in 2004–2008) cohorts. We defined as guidelines-inconsistent during PHI and CHI, patients meeting criteria for ART initiation and not treated in the following month and during the next 6 months, respectively.Results
ART initiation during PHI dramatically decreased from 91% of patients in 1996–99 to 22% in 2007 and increased to 60% in 2010, following changes in recommendations. In 2007, however, after the CD4 count threshold was raised to 350 cells/mm3 in 2006, only 55% of the patients with CD4≤350 were treated and 66% in 2008. During CHI, ART was more frequently initiated in patients who met the criteria at entry (96%) than during follow-up: 83% when recommendation to treat was 200 and 73% when it was 350 cells/mm3. Independent risk factors for not being treated during CHI despite meeting the criteria were lower viral load, lower educational level, and poorer living conditions.Conclusion
HIV ART initiation guidelines are largely followed by practitioners in France. What can still be improved, however, is time to treat when CD4 cell counts reach the threshold to treat. Risk factors for lack of timely treatment highlight the need to understand better how patients’ living conditions and physicians’ perceptions influence the decision to initiate treatment. 相似文献3.
Marjorie S. Hong Evguenia Rainina Janet K. Grimsley Bruce E. Dale James R. Wild 《Bioremediation Journal》1998,2(2):145-157
A genetically engineered strain of Escherichia coli that expresses organophosphorus hydrolase (OPH) was immobilized in a polyvinyl alcohol (PVA) cryogel to form a porous biocatalyst that successfully degrades organophosphorus (OP) neurotoxins. The impacts of both diffusion and reaction on biocatalyst efficiency were determined to enable prediction and optimization of the biocatalyst performance. The kinetic rate parameters and activation energies of pure OPH, free cell suspensions, and the immobilized cell biocatalyst were compared. Diffusion was a determining factor for paraoxon hydrolysis because of the very rapid OPH kinetics for its model substrate. Both the paraoxon diffusion through the PVA matrix and the diffusion associated with microbial transport of paraoxon were shown to impact the biocatalyst reaction. However, the enhancement in storage stability resulting from diffusional limitations provides an advantage to diffusion-limited operation. This research may serve as a guide to define the influence of diffusion in biological reaction systems. The broad substrate specificity and hydrolytic efficiency of OPH coupled with the ability to genetically engineer the enzyme for specific target OP neurotoxins enhance the suitability of OPH-based technologies for detoxification of these compounds. Cryoimmobilization provides a suitable vehicle as a cost-effective, efficient technology for bioremediation of environmental media contaminated with OP compounds. 相似文献
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Georges M. Pavlov Evguenia V. Korneeva Natalia A. Smolina Ulrich S. Schubert 《European biophysics journal : EBJ》2010,39(3):371-379
Three well-known representatives of the cyclodextrin family were completely characterized by molecular hydrodynamics methods
in three different solvents. For the first time the possibility of an estimation of velocity sedimentation coefficients s between 0.15 and 0.5 S by the numerical solution of the Lamm equation is shown. Comparison of the experimental hydrodynamic
characteristics of the cyclodextrins with theoretical calculations for toroidal molecules allows an estimation of the thickness
of the solvent layers on the surface of cyclodextrin molecules. 相似文献
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7.
Perkowski S Scherpereel A Murciano JC Arguiri E Solomides CC Albelda SM Muzykantov V Christofidou-Solomidou M 《American journal of physiology. Lung cellular and molecular physiology》2006,291(5):L1050-L1058
The objective of this study was to quantitatively assess changes in cell adhesion molecule (CAM) expression on the pulmonary endothelial surface during hyperoxia and to assess the functional significance of those changes on cellular trafficking and development of oxygen-induced lung injury. Mice were placed in >95% O(2) for 0-72 h, and pulmonary injury and neutrophil (PMN) sequestration were assessed. Specific pulmonary CAM expression was quantified with a dual-radiolabeled MAb technique. To test the role of CAMs in PMN trafficking during hyperoxia, blocking MAbs to murine P-selectin, ICAM-1, or platelet-endothelial cell adhesion molecule-1 (PECAM-1) were injected in wild-type mice. Mice genetically deficient in these CAMs and PMN-depleted mice were also evaluated. PMN sequestration occurred within 8 h of hyperoxia, although alveolar emigration occurred later (between 48 and 72 h), coincident with rapid escalation of the lung injury. Hyperoxia significantly increased pulmonary uptake of radiolabeled antibodies to P-selectin, ICAM-1, and PECAM-1, reflecting an increase in their level on pulmonary endothelium and possibly sequestered blood cells. Although both anti-PECAM-1 and anti-ICAM-1 antibodies suppressed PMN alveolar influx in wild-type mice, only mice genetically deficient in PECAM-1 showed PMN influx suppression. Neither CAM blockade, nor genetic deficiency, nor PMN depletion attenuated lung injury. We conclude that early pulmonary PMN retention during hyperoxia is not temporally associated with an increase in endothelial CAMs; however, subsequent PMN emigration into the alveolar space may be supported by PECAM-1 and ICAM-1. Blocking PMN recruitment did not prevent lung injury, supporting dissociation between PMN infiltration and lung injury during hyperoxia in mice. 相似文献
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Bekman EP Saibo NJ Di Cataldo A Regalado AP Ricardo CP Rodrigues-Pousada C 《Planta》2000,211(5):663-672
1-Aminocyclopropane-1-carboxylate (ACC) synthase (ACS; EC 4.4.1.14) is the key regulatory enzyme of the ethylene biosynthetic
pathway and is encoded by a multigene family in Arabidopsis thaliana, tomato, mung bean and other plants. Southern blot analysis revealed the existence of at least five ACS genes in white lupin
(Lupinus albus L.) genome. Four complete and one partial sequences representing different ACS genes were cloned from the lupin genomic library.
The levels of expression of two of the genes, LA-ACS1 and LA-ACS3, were found to increase after hypocotyl wounding. Apparently, these two genes were up-regulated by exogenous IAA treatment
of seedlings. The LA-ACS3 mRNA levels were also elevated in the apical part of hypocotyl, which is reported to contain a high endogenous auxin concentration.
This gene may be involved in the auxin- and ethylene-controlled apical hook formation. The expression of the LA-ACS4 gene was found to be almost undetectable. This gene may represent a “silent” twin of LA-ACS5 as these two genes share a considerable level of homology in coding and non-coding regions. The LA-ACS5 mRNA is strongly up-regulated in the embryonic axis of germinating seeds at the time of radicle emergence, and was also found
in roots and hypocotyls of lupin seedlings.
Received: 19 July 1999 / Accepted: 3 March 2000 相似文献
10.
Svarovskaia ES Barr R Zhang X Pais GC Marchand C Pommier Y Burke TR Pathak VK 《Journal of virology》2004,78(7):3210-3222
We previously found that azido-containing beta-diketo acid derivatives (DKAs) are potent inhibitors of human immunodeficiency virus type 1 (HIV-1) integrase (IN) (X. Zhang et al., Bioorg. Med. Chem. Lett., 13:1215-1219, 2003). To characterize the intracellular mechanisms of action of DKAs, we analyzed the antiviral activities of two potent azido-containing DKAs with either a monosubstitution or a disubstitution of azido groups, using single- and multiple-replication-cycle assays. Both azido-containing DKAs significantly inhibited HIV-1 infection in 293T, CEM-SS, and H9 cells (50% inhibitory concentration = 2 to 13 micro M) and exhibited low cytotoxicity (50% cytotoxic concentration = 60 to 600 micro M). Inhibition of HIV-1 IN in vivo was demonstrated by the observation that previously described L-708,906 resistance mutations in HIV-1 IN (T66I and T66I/S153Y) also conferred resistance to the azido-group-containing DKAs. In vitro assays and in vivo analysis indicated that the DKAs did not significantly inhibit the 3' processing and selectively inhibited the strand transfer reaction. In addition, quantitative PCR indicated that two-long-terminal-repeat (2-LTR) circles were elevated in the presence of the azido-containing DKAs, confirming that HIV-1 IN was the intracellular target of viral inhibition. To gain insight into the mechanism by which the DKAs increased 2-LTR-circle formation of 3'-processed viral DNAs, we performed extensive DNA sequencing analysis of 2-LTR-circle junctions. The results indicated that the frequency of deletions at the circle junctions was elevated from 19% for the untreated controls to 32 to 41% in the presence of monosubstituted (but not disubstituted) DKAs. These results indicate that the structure of the DKAs can influence the extent of degradation of viral DNA ends by host nucleases and the frequency of deletions at the 2-LTR-circle junctions. Thus, sequencing analysis of 2-LTR-circle junctions can elucidate the intracellular mechanisms of action of HIV-1 IN inhibitors. 相似文献