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61.
Chris Petucci Tom Lloyd Heather A. Harris Xiaochun Zhang Vargheese M. Chennathukuzhi Belew Mekonnen Yanxuan Cai 《Journal of mass spectrometry : JMS》2010,45(1):65-71
A sensitive LC/MS/MS method has been developed by derivatization of 17β‐estradiol (E2) with dansyl chloride to quantitate 17β‐E2 in female rat serum. The use of E2‐d5 minimized interferences from endogenous 17β‐E2 in order to achieve a limit of quantitation (LOQ) of 2.5 pg/ml using 150 µl of female rat serum. The recovery of the dansyl derivative was 95% or greater in quality control samples. The intra and interday assay precision was better than 8.2 and 6.2%, respectively, with accuracies ranging from 97 to 101% in the quality control samples. The assay was used for the quantitation of serum E2 as a biomarker for the estrogen receptor (ER) antagonist activity of small molecule SERMs (selective estrogen receptor modulators) in the female rat brain. The study revealed that a statistically significant upregulation of serum 17β‐E2 occurred for rats dosed with SERMs that are known to penetrate the brain and disrupt the hypothalamic‐pituitary‐ovarian (HPO) axis. Variations in 17β‐E2 in ascending dose studies also correlated with the corresponding trends in CYP17a1 levels, an mRNA biomarker for ovarian hyperstimulation. This biomarker assay has provided a useful screen for medicinal chemistry optimization to produce SERMs that do not interfere with negative feedback of estrogens on the brain and for biological hypothesis testing. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
62.
Yunsen Li Emma Arigi Heather Eichert Steven B. Levery 《Journal of mass spectrometry : JMS》2010,45(5):504-519
A method for generation of novel fluorocarbon derivatives of glycosphingolipids (GSLs) with high affinity for fluorocarbon phases has been developed, and their potential applications to mass spectrometry (MS)‐based methodologies for glycosphingolipidomics have been investigated. Sphingolipid ceramide N‐deacylase (SCDase) is used to remove the fatty acid from the ceramide moiety, after which a fluorocarbon‐rich substituent (F‐Tag) is incorporated at the free amine of the sphingoid. In initial trials, a neutral GSL, globotriaosylceramide (Gb3Cer), three purified bovine brain gangliosides, and four fungal glycosylinositol phosphorylceramides (GIPCs) were de‐N‐acylated, derivatized by prototype F‐Tags, and recovered by solid phase extraction on fluorocarbon‐derivatized silica (F‐SPE). The efficacy of SCDase treatment of GIPCs was here demonstrated for the first time. Compatibility with subsequent per‐N,O‐methylation was established for the F‐tagged Gb3 Cer and purified gangliosides, and extensive mass spectra (MS1 and MS2) consistent with all of the expected products were acquired. The potential use of F‐tagged derivatives for a comprehensive MS based profiling application was then demonstrated on a crude ganglioside mixture extracted from bovine brain. Finally, a simple trial in microarray format demonstrated fixation of F‐tagged GM1 ganglioside to a fluorous glass surface, with the glycan intact and available for interaction with a fluorescent derivative of cholera toxin B chain. The methods described thus provide a new avenue for rapid GSL recovery or cleanup, potentially compatible with a variety of platforms for mass spectrometric profiling and structure analysis, as well as parallel analysis of functional interactions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
63.
Alexander Malugin Heather Herd Hamidreza Ghandehari 《Journal of nanoparticle research》2011,13(10):5381-5396
The objective of this study was to evaluate the influence of size and surface functionality of amorphous silica nanoparticles
(SNPs) on their interaction with cultured cells. The intracellular uptake, phagocytic activity, and possible mechanisms of
toxicity induced by SNPs were studied on murine alveolar macrophages and two epithelial cancer cell lines. It was found that
phagocytic cells are more susceptible to amorphous SNPs than epithelial cells. SNPs with functionalized surfaces were capable
to induce the formation of apoptotic cells to a higher extent than plain particles. Plain SNPs induced plasma membrane damage
in phagocytic cells to a higher extent and caused cell death in a shorter period of time than surface-functionalized SNPs.
The prevalence of necrotic mode of cell death was observed after treatment with plain SNPs. In the range studied surface functionality
played an important role in SNPs toxicity. 相似文献
64.
F. Migliorini K. A. Thomson G. J. Smallwood 《Applied physics. B, Lasers and optics》2011,104(2):273-283
The optical properties of soot, in particular the propensity of soot to absorb and scatter light as a function of wavelength,
are key parameters for the correct interpretation of soot optical diagnostics. An overview of the data available in the literature
highlights the differences in the reported optical properties of aging soot. In many cases, the properties of mature soot
are used when evaluating in-flame soot but this assumption might not be suitable for all conditions and should be checked.
This need has been demonstrated by performed spectral resolved line-of-sight attenuation (Spec-LOSA) measurements on an ethylene/air
premixed and non-premixed flame. Transmission electron microscopy of thermophoretically sampled soot was also performed to
qualify the soot aging and to establish soot morphology in order to correct light extinction coefficients for the scattering
contribution. The measured refractive index absorption function, E(m)
λ
, showed a very strong spectral dependence which also varied with height above the burner for both flames. However, above
700 nm, the slope of the refractive index function was near zero for both flames and all measurement heights. The upper visible
and near infrared wavelengths are therefore recommended for soot optical measurements. 相似文献
65.
M. Köhler K. P. Geigle W. Meier B. M. Crosland K. A. Thomson G. J. Smallwood 《Applied physics. B, Lasers and optics》2011,104(2):409-425
Computational fluid dynamics (CFD) modelers require high-quality experimental data sets for validation of their numerical
tools. Preferred features for numerical simulations of a sooting, turbulent test case flame are simplicity (no pilot flame),
well-defined boundary conditions, and sufficient soot production. This paper proposes a non-premixed C2H4/air turbulent jet flame to fill this role and presents an extensive database for soot model validation. 相似文献
66.
K. A. Thomson K. P. Geigle M. Köhler G. J. Smallwood D. R. Snelling 《Applied physics. B, Lasers and optics》2011,104(2):307-319
To investigate the transient change of soot optical properties resulting from pulsed laser heating of soot in a cooled exhaust
plume we have simultaneously performed cw light extinction at 405 and 830 nm and elastic light scattering at 1064 nm. A reversible
increase to the 830-nm light extinction of up to 7%, observed during the time period where the soot was hot, suggests a temperature-dependent
light absorption refractive index function, E(m
λ
). At low fluence, small permanent increases of E(m
λ
) of <2% were also observed. 405-nm extinction measurements revealed that the soot likely contained material which continued
to absorb 405-nm radiation when desorbed, thus complicating measurement interpretation. 1064-nm light scattering measurements
showed a gradual decrease of scattering propensity with increasing laser fluence up to the point of material loss, which is
consistent with the expected decrease of the structure factor of the soot aggregates as they expand. It is concluded that
variations of the optical properties are occurring at the time of laser-induced incandescence (LII) emission, which should
be accounted for in time-resolved LII measurement interpretation. 相似文献
67.
Heather Lynn Johnson Glendon W. Blume Jeanne K. Shimizu Duane Graysay Svetlana Konnova 《Mathematical Thinking and Learning》2014,16(4):285-311
To contribute to an understanding of the nature of teachers’ mathematical knowledge and its role in teaching, the case study reported in this article investigated a teacher’s conception of a metamathematical concept, definition, and her use of examples in doing and teaching mathematics. Using an enactivist perspective on mathematical knowledge, the authors give an account of the case of Lily, a prospective, then beginning, teacher who conceived of mathematical definition as an object with particular form and function and engaged in purposeful, specialized use of examples when doing and teaching mathematics. Lily’s case illustrates how a teacher’s interpretation of examples (as exemplifications or single instances) and conception of the form and function of definitions can influence her doing and teaching mathematics. An implication is that teacher preparation should foster teachers’ abilities to use examples purposefully to provide students with rich opportunities to engage in mathematical processes such as defining. 相似文献
68.
69.
70.
Heather Russell 《Advances in Mathematics》2003,179(1):38-58
We give a method of counting the number of curves with a given type of singularity in a suitably ample linear series on a smooth surface using punctual Hilbert schemes. The types of singularities for which our results suffice include the topological type with local equation xa+yb with ?a?3b. We work out the example of curves with the analytic type of singularity with local equation x2+yn for 1<n<9. 相似文献