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排序方式: 共有450条查询结果,搜索用时 15 毫秒
1.
Eric Moulton Mélika Amor-Sahli Vincent Perlbarg Christine Pires Sophie Crozier Damien Galanaud Romain Valabregue Marion Yger Flore Baronnet-Chauvet Yves Samson Didier Dormont Charlotte Rosso 《PloS one》2015,10(11)
Fractional anisotropy (FA) is an effective marker of motor outcome at the chronic stage of stroke yet proves to be less efficient at early time points. This study aims to determine which diffusion metric in which location is the best marker of long-term stroke outcome after thrombolysis with diffusion tensor imaging (DTI) at 24 hours post-stroke. Twenty-eight thrombolyzed patients underwent DTI at 24 hours post-stroke onset. Ipsilesional and contralesional FA, mean (MD), axial (AD), and radial (RD) diffusivities values were calculated in different Regions-of-Interest (ROIs): (1) the white matter underlying the precentral gyrus (M1), (2) the corona radiata (CoRad), (3) the posterior limb of the internal capsule (PLIC) and (4) the cerebral peduncles (CP). NIHSS scores were acquired at admission, day 1, and day 7; modified Rankin Scores (mRS) at 3 months. Significant decreases were found in FA, MD, and AD of the ipsilesional CoRad and M1. MD and AD were also significantly lower in the PLIC. The ratio of ipsi and contralesional AD of the CoRad (CoRad-rAD) was the strongest diffusion parameter correlated with motor NIHSS scores on day 7 and with the mRS at 3 months. A Receiver-Operator Curve analysis yielded a model for the CoRad-rAD to predict good outcome based on upper limb NIHSS motor scores and mRS with high specificity and sensitivity. FA values were not correlated with clinical outcome. In conclusion, axial diffusivity of the CoRad from clinical DTI at 24 hours post-stroke is the most appropriate diffusion metric for quantifying stroke damage to predict outcome, suggesting the importance of early axonal damage. 相似文献
2.
Production of gibberellins and indole-3-acetic acid by Rhizobium phaseoli in relation to nodulation of Phaseolus vulgaris roots 总被引:2,自引:0,他引:2
Similar ranges of gibberellins (GAs) were detected by high-performance liquid chromatography (HPLC)-immunoassay procedures in ten cultures of wild-type and mutant strains of Rhizobium phaseoli. The major GAs excreted into the culture medium were GA1 and GA4. These identifications were confirmed by combined gas chromatographymass spectrometry. The HPLC-immunoassays also detected smaller amounts of GA9- as well as GA20-like compounds, the latter being present in some but not all cultures. In addition to GAs, all strains excreted indole-3-acetic acid (IAA) but there was no obvious relationship between the amounts of GA and IAA that accumulated. The Rhizobium strains studied included nod
– and fix
– mutants, making it unlikely that the IAA- and GA-biosynthesis genes are closely linked to the genes for nodulation and nitrogen fixation.The HPLC-immunoassay analyses showed also that nodules and non-nodulated roots of Phaseolus vulgaris L. contained similar spectra of GAs to R. phaseoli culture media. The GA pools in roots and nodules were of similar size, indicating that Rhizobium does not make a major contribution to the GA content of the infected tissue.Abbreviations EIA
enzyme immunoassay
- GAn
gibberellin An
- GC-MS
gas chromatography-mass spectrometry
- HPLC
high-performance liquid chromatography
- IAA
indole-3-acetic acid
- Me
methyl ester
- RIA
radioimmunoassay
- TLC
thin-layer chromatography 相似文献
3.
4.
The Hymenoptera (ants, bees, wasps and sawflies) display a great variety of social systems and sex ratios and have played a key role in the development and testing of many evolutionary models. Traditionally, considerable emphasis was placed on the fact that hymenopterans have haploid males and diploid females but it is now clear that many species also regularly produce sterile, diploid males. Recent studies explore the diverse ways in which production of these diploid males influences selection on mating systems, sex ratios and social behaviour. 相似文献
5.
Atlantic salmon survival in the R. Bush (N. Ireland) from egg to summer 0+ was inversely density-dependent on egg deposition ( P <0.05). A stock-recruitment relationship derived from egg deposition and summer 0+ abundance index data was compared to that derived from adult and smolt counts based on total trapping. Fitted Ricker curves indicated maximum recruitment at around 2.35 million eggs and 2.46 million eggs for 0+ index and smolt count methods, respectively. Salmon 0+ abundance index data from semi-quantitative electrofishing could be obtained with relatively little effort, and used to derive whole-river stock-recruitment relationships on rivers where only adult count or some other estimator of parental stock is available. The derivation and expression of spawning targets from stock/recruitment relationships is discussed with reference to the R. Bush data. 相似文献
6.
An abundance index for 0+ Atlantic salmon was based on semi-quantitative electrofishing estimates at 137 sites in typical juvenile habitat throughout the River Bush (N. Ireland). 0 + abundance was linearly related to total smolt numbers migrating through a downstream trap in subsequent years ( r 2 = 0.716, P <0.001), suggesting a high degree of predictive ability. This predictive ability decreased as smolt age increased, suggesting influence of density-independent mortality. Potential application of the technique to estimate smolt production from rivers having no trapping facilities is discussed, together with sources of variability potentially affecting estimates. 相似文献
7.
8.
The use of spectrofluorimeter coupled to a reverse phase high performance liquid chromatography column permits selective detection of indole-3-acetic acid at the low picogram level. The value of the technique is demonstrated by the analysis of endogenous IAA in elongating shoots, xylem sap and callus of Douglas-fir. The data are also used to illustrate a procedure whereby the accuracy of chromatographic analyses can be verified within definable probability limits.Abbreviations GC-MS
combined gas chromatography-mass spectrometry
- HPLC
high performance liquid chromatography
- IAA
indole-3-acetic acid
- SEC
steric exclusion chromatography
- SICM
selected ion current monitoring
Technical Paper No. 5379 from the Oregon State University Agricultural Experiment Station 相似文献
9.
Metabolism of Caffeine and Related Purine Alkaloids in Leaves of Tea (Camellia sinensis L.) 总被引:3,自引:0,他引:3
Purine alkaloid catabolism pathways in young, mature and agedleaves of tea (Camellia sinensis L.) were investigated by incubatingleaf sections with 14C-labelled theobromine, caffeine, theophyllineand xanthine. Incorporation of label into CO2 was determinedand methanol-soluble metabolites were analysed by high-performanceliquid chromatography-radiocounting and thin layer chro-matography.The data obtained demonstrate that theobromine is the immediateprecursor of caffeine, which accumulates in tea leaves becauseits conversion to theophylline is the rate limiting step inthe purine alkaloid catabolism pathway. The main fate of [8-14C]theophyllineincubated with mature and aged leaves, and to a lesser extentyoung leaves, is conversion to 3-methylxanthine and onto xanthinewhich is degraded to 14CO2 via the purine catabolism pathway.However, with young leaves, sizable amounts of [8-14C]-theophyllinewere salvaged for the synthesis of caffeine via a 3-methylxanthine 相似文献
10.