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排序方式: 共有466条查询结果,搜索用时 18 毫秒
51.
Sonia Lewycka Charles Mwansambo Peter Kazembe Tambosi Phiri Andrew Mganga Mikey Rosato Hilda Chapota Florida Malamba Stefania Vergnano Marie-Louise Newell David Osrin Anthony Costello 《Trials》2010,11(1):1-15
Background
Paclitaxel-eluting stents decrease angiographic and clinical restenosis following percutaneous coronary intervention compared to bare metal stents. TAXUS Element is a third-generation paclitaxel-eluting stent which incorporates a novel, thinner-strut, platinum-enriched metal alloy platform. The stent is intended to have enhanced radiopacity and improved deliverability compared to other paclitaxel-eluting stents. The safety and efficacy of the TAXUS Element stent are being evaluated in the pivotal PERSEUS clinical trials.Methods/Design
The PERSEUS trials include two parallel studies of the TAXUS Element stent in single, de novo coronary atherosclerotic lesions. The PERSEUS Workhorse study is a prospective, randomized (3:1), single-blind, non-inferiority trial in subjects with lesion length ≤28 mm and vessel diameter ≥2.75 mm to ≤4.0 mm which compares TAXUS Element to the TAXUS Express2 paclitaxel-eluting stent system. The Workhorse study employs a novel Bayesian statistical approach that uses prior information to limit the number of study subjects exposed to the investigational device and thus provide a safer and more efficient analysis of the TAXUS Element stent. PERSEUS Small Vessel is a prospective, single-arm, superiority trial in subjects with lesion length ≤20 mm and vessel diameter ≥2.25 mm to <2.75 mm that compares TAXUS Element with a matched historical bare metal Express stent control.Discussion
The TAXUS PERSEUS clinical trial program uses a novel statistical approach to evaluate whether design and metal alloy iterations in the TAXUS Element stent platform provide comparable safety and improved procedural performance compared to the previous generation Express stent. PERSEUS trial enrollment is complete and primary endpoint data are expected in 2010. PERSEUS Workhorse and Small Vessel are registered at http://www.clinicaltrials.gov, identification numbers NCT00484315 and NCT00489541. 相似文献52.
Use of digital webcam images to track spring green-up in a deciduous broadleaf forest 总被引:6,自引:0,他引:6
Richardson AD Jenkins JP Braswell BH Hollinger DY Ollinger SV Smith ML 《Oecologia》2007,152(2):323-334
Understanding relationships between canopy structure and the seasonal dynamics of photosynthetic uptake of CO2 by forest canopies requires improved knowledge of canopy phenology at eddy covariance flux tower sites. We investigated whether
digital webcam images could be used to monitor the trajectory of spring green-up in a deciduous northern hardwood forest.
A standard, commercially available webcam was mounted at the top of the eddy covariance tower at the Bartlett AmeriFlux site.
Images were collected each day around midday. Red, green, and blue color channel brightness data for a 640 × 100-pixel region-of-interest
were extracted from each image. We evaluated the green-up signal extracted from webcam images against changes in the fraction
of incident photosynthetically active radiation that is absorbed by the canopy (f
APAR), a broadband normalized difference vegetation index (NDVI), and the light-saturated rate of canopy photosynthesis (A
max), inferred from eddy flux measurements. The relative brightness of the green channel (green %) was relatively stable through
the winter months. A steady rising trend in green % began around day 120 and continued through day 160, at which point a stable
plateau was reached. The relative brightness of the blue channel (blue %) also responded to spring green-up, although there
was more day-to-day variation in the signal because blue % was more sensitive to changes in the quality (spectral distribution)
of incident radiation. Seasonal changes in blue % were most similar to those in f
APAR and broadband NDVI, whereas changes in green % proceeded more slowly, and were drawn out over a longer period of time. Changes
in A
max lagged green-up by at least a week. We conclude that webcams offer an inexpensive means by which phenological changes in
the canopy state can be quantified. A network of cameras could offer a novel opportunity to implement a regional or national
phenology monitoring program. 相似文献
53.
54.
MicroRNA-133 controls cardiac hypertrophy 总被引:23,自引:0,他引:23
55.
Novel blocker of NFAT activation inhibits IL-6 production in human myometrial arteries and reduces vascular smooth muscle cell proliferation 总被引:1,自引:0,他引:1
56.
The interaction between a cationic poly(amido amine) (PAMAM) dendrimer of generation 4 and double-stranded salmon sperm DNA in 10 mM NaBr solution has been investigated using dynamic light scattering (DLS) and steady-state fluorescence spectroscopy. The structural parameters of the formed aggregates as well as the complex formation process were studied in dilute solutions. When DNA is mixed with PAMAM dendrimers, it undergoes a transition from a semiflexible coil to a more compact conformation due to the electrostatic interaction present between the cationic dendrimer and the anionic polyelectrolyte. The DLS results reveal that one salmon sperm DNA molecule forms a discrete aggregate in dilute solution with several PAMAM dendrimers with a mean apparent hydrodynamic radius of 50 nm. These discrete complexes coexist with free DNA at low molar ratios of dendrimer to DNA, which shows that cooperativity is present in the complex formation. The formation of the complexes was confirmed by agarose gel electrophoresis measurements. DNA in the complexes was also found to be significantly more protected against DNase catalyzed digestion compared to free DNA. The number of dendrimers per DNA chain in the complexes was found to be approximately 35 as determined by steady-state fluorescence spectroscopy. 相似文献
57.
Chringma Sherpa Jason W. Rausch Stuart F.J. Le?Grice Marie-Louise Hammarskjold David Rekosh 《Nucleic acids research》2015,43(9):4676-4686
The HIV Rev protein forms a complex with a 351 nucleotide sequence present in unspliced and incompletely spliced human immunodeficiency virus (HIV) mRNAs, the Rev response element (RRE), to recruit the cellular nuclear export receptor Crm1 and Ran-GTP. This complex facilitates nucleo-cytoplasmic export of these mRNAs. The precise secondary structure of the HIV-1 RRE has been controversial, since studies have reported alternative structures comprising either four or five stem-loops. The published structures differ only in regions that lie outside of the primary Rev binding site. Using in-gel SHAPE, we have now determined that the wt NL4-3 RRE exists as a mixture of both structures. To assess functional differences between these RRE ‘conformers’, we created conformationally locked mutants by site-directed mutagenesis. Using subgenomic reporters, as well as HIV replication assays, we demonstrate that the five stem-loop form of the RRE promotes greater functional Rev/RRE activity compared to the four stem-loop counterpart. 相似文献
58.
Cushing TD Baichwal V Berry K Billedeau R Bordunov V Broka C Browner MF Cardozo M Cheng P Clark D Dalrymple S DeGraffenreid M Gill A Hao X Hawley RC He X Labadie SS Labelle M Lehel C Lu PP McIntosh J Miao S Parast C Shin Y Sjogren EB Smith ML Talamas FX Tonn G Walker KM Walker NP Wesche H Whitehead C Wright M Jaen JC 《Bioorganic & medicinal chemistry letters》2011,21(1):423-426
A novel series of (E)-1-((2-(1-methyl-1H-imidazol-5-yl) quinolin-4-yl) methylene) thiosemicarbazides was discovered as potent inhibitors of IKKβ. In this Letter we document our efforts at further optimization of this series, culminating in 2 with submicromolar potency in a HWB assay and efficacy in a CIA mouse model. 相似文献
59.
Innala L Möller B Ljung L Magnusson S Smedby T Södergren A Öhman ML Rantapää-Dahlqvist S Wållberg-Jonsson S 《Arthritis research & therapy》2011,13(4):R131
Introduction
Co-morbidity and mortality due to cardiovascular disease (CVD) are increased in patients with rheumatoid arthritis (RA). Most published studies in this field are retrospective or cross sectional. We investigated the presence of traditional and disease related risk factors for CVD at the onset of RA and during the first five years following diagnosis. We also evaluated their potential for predicting a new cardiovascular event (CVE) during the five-year follow-up period and the modulatory effect of pharmacological treatment. 相似文献60.
Most eukaryotes have at least some genes interrupted by introns. While it is well accepted that introns were already present at moderate density in the last eukaryote common ancestor, the conspicuous diversity of intron density among genomes suggests a complex evolutionary history, with marked differences between phyla. The question of the rates of intron gains and loss in the course of evolution and factors influencing them remains controversial. We have investigated a single gene family, alpha-amylase, in 55 species covering a variety of animal phyla. Comparison of intron positions across phyla suggests a complex history, with a likely ancestral intronless gene undergoing frequent intron loss and gain, leading to extant intron/exon structures that are highly variable, even among species from the same phylum. Because introns are known to play no regulatory role in this gene and there is no alternative splicing, the structural differences may be interpreted more easily: intron positions, sizes, losses or gains may be more likely related to factors linked to splicing mechanisms and requirements, and to recognition of introns and exons, or to more extrinsic factors, such as life cycle and population size. We have shown that intron losses outnumbered gains in recent periods, but that "resets" of intron positions occurred at the origin of several phyla, including vertebrates. Rates of gain and loss appear to be positively correlated. No phase preference was found. We also found evidence for parallel gains and for intron sliding. Presence of introns at given positions was correlated to a strong protosplice consensus sequence AG/G, which was much weaker in the absence of intron. In contrast, recent intron insertions were not associated with a specific sequence. In animal Amy genes, population size and generation time seem to have played only minor roles in shaping gene structures. 相似文献