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991.
Yingyongnarongkul BE Howarth M Elliott T Bradley M 《Journal of combinatorial chemistry》2004,6(5):753-760
The solid-phase synthesis of a library of arginine-containing lipid transfection agents on high-loading beads is described. The transfection activity of the cationic lipids was determined using compound cleaved from single beads (single-bead screening) and showed, in some cases, comparable or higher DNA transfection activities as compared to commercially available reagents. Lipids with one arginine headgroup and a cholesterol tail were found to be the most active, even though their DNA binding strength (retardation assays) was relatively weak. Single-bead screening of transfection activity facilitates the rapid analysis of libraries of transfection reagents and will allow the rapid optimization of gene delivery into cells, both in culture and in vivo. 相似文献
992.
Hu H Bradley SA Krishnamurthy K 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,171(2):247-206
Compared to its 2D counterpart, the selective 1D NOESY experiment offers greatly simplified spectral interpretation and is invaluable to the structure elucidation of small-to-medium sized molecules, although its application is limited to well-resolved resonances only. The doubly selective 1D TOCSY-NOESY experiment allows the 1D NOESY experiment to be extended to resonances within overlapped spectral regions. However, existing methods do not address the critical issue of zero-quantum interference, which leads to severe anti-phase distortions to the line shape of scalar coupled spins and often complicates the identification of weak NOE enhancements. In this communication, we describe an improved selective TOCSY edited preparation (STEP) function and its application to the selective 1D NOESY experiment. The STEP function incorporates a novel zero-quantum filter introduced by Thrippleton and Keeler [Angew. Chem. Int. Ed. 42 (2003) 3938], which permits essentially complete suppression of zero-quantum coherence in a single scan. Residual anti-phase distortions due to spin-state mixing are removed using the double difference methodology reported by Shaka et al. [45th Experimental NMR Conference, Pacific Grove, USA, 2004]. The combined use of these techniques ensures that the final spectra are free of distortions, which is crucial to the reliable detection of weak NOE enhancements. Although employed as an additional preparation period in the example demonstrated here, the STEP function affords a general editing tool for spectral simplification and can be applied to a range of experiments. 相似文献
993.
Richard C Bradley 《Journal of Combinatorial Theory, Series B》1978,24(3):311-317
By using color interchanges, we prove statements like the following: If G is a simple cubic graph whose edges cannot be 3-colored, and W is a 5-circuit of G, then the number of edge-3-colorings of G-W with three given colors is a multiple of 5. 相似文献
994.
Synthesis of 7-(N,N′-trimethyl)-5-methoxytryptamine from 2,5-dimethylpyrone via 4-methoxy-2,6-dimelhylnitrobenzene and 5-melhoxy-7-methylindole is described. 相似文献
995.
Díaz-Mochón JJ Bialy L Keinicke L Bradley M 《Chemical communications (Cambridge, England)》2005,(11):1384-1386
Enzymatic modifications of split and mix libraries were followed by "pulling down" onto a 2-dimensional DNA microarray, via PNA tagging; this allowed complete library interrogation of all members of the split and mix library. 相似文献
996.
Bradley SA Hu H Krishnamurthy K Hadden CE 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,174(1):110-115
We describe a unique band-selective method that utilizes a selective composite gradient to simultaneously achieve band selection and coherence pathway selection. This element is similar to the composite gradient known as the CLUB sandwich except the original broadband pulses have been replaced with selective pulses and the strengths of the antipolar gradients have been unbalanced. In this way, only the signals within the inversion band will continue to dephase throughout the duration of the element and satisfy the proper encoding-to-decoding gradient ratio necessary for coherence selection. Apart from the inverted polarity and asymmetry of the gradients, the band-selective CLUB sandwich is identical to the DPFGSE sequence and provides many of its desirable characteristics. We have successfully incorporated the band-selective CLUB into the DQF-COSY pulse sequence to create a band-selective experiment that offers the selectivity desired for resolution enhancement while maintaining excellent phase behavior. This is demonstrated on the congested aliphatic region of the ionophorous antibiotic Lasalocid A. 相似文献
997.
A sharp base B is a base such that whenever (Bi)i<ω is an injective sequence from B with x∈?i<ωBi, then is a base at x. Alleche, Arhangel'ski? and Calbrix asked: if X has a sharp base, must X×[0,1] have a sharp base? Good, Knight and Mohamad claimed to construct an example of a Tychonoff space P with a sharp base such that P×[0,1] does not have a sharp base. However, the space was not regular. We show how to modify the construction to make P Tychonoff. 相似文献
998.
Murphy AT Brown-Augsburger P Yu RZ Geary RS Thibodeaux S Ackermann BL 《European journal of mass spectrometry (Chichester, England)》2005,11(2):209-215
A quantitative method for the determination of a partially modified, 2'-ribose alkoxy 18-mer phosphorothioate oligonucleotide, in liver tissue has been developed. A liquid:liquid extraction, ion-pair reverse phase chromatographic separation, and tandem mass spectrometry were used to achieve a quantitation range of 125 to 10,000 ng g(-1) mouse liver tissue. A total cycle time of 5 min was obtained while maintaining separation of three potential impurities. Separations were performed using a Discovery RP-Amide C16, 100 x 2 mm column packed with 5 microm particles. The separation was facilitated by the use of triethylamine (TEA) and hexafluoroisopropanol (HFIP) as ion-pair agents. The method has subsequently been used for the determination of other phosphorothioate oligonucleotides in support of discovery research. 相似文献
999.
Bradley J Turner Dirk Bäumer Nicholas J Parkinson Jakub Scaber Olaf Ansorge Kevin Talbot 《BMC neuroscience》2008,9(1):104
Background
Redistribution of nuclear TAR DNA binding protein 43 (TDP-43) to the cytoplasm and ubiquitinated inclusions of spinal motor neurons and glial cells is characteristic of amyotrophic lateral sclerosis (ALS) pathology. Recent evidence suggests that TDP-43 pathology is common to sporadic ALS and familial ALS without SOD1 mutation, but not SOD1-related fALS cases. Furthermore, it remains unclear whether TDP-43 abnormalities occur in non-ALS forms of motor neuron disease. Here, we characterise TDP-43 localisation, expression levels and post-translational modifications in mouse models of ALS and spinal muscular atrophy (SMA). 相似文献1000.
Kropewnicki ML Schaefer DJ Hehn M Dermaut W Geise HJ Chmelka BF 《Solid state nuclear magnetic resonance》2002,22(2-3):275-297
The properties of poly(p-phenylene vinylene) (PPV) films depend on the degree of orientational order present in the films. Recently, Dermaut et al. reported a novel cold-stretching technique (Macromolecules 33, 5634-5637 (2000)) in which chain alignment can be introduced into PPV precursor films by uniaxially stretching them prior to the thermal elimination reaction that forms PPV. The two-dimensional direction exchange with correlation for orientation-distribution evaluation and reconstruction (DECODER) 13C NMR technique was applied to both unstretched PPV films and PPV films that were uniaxially cold stretched to a draw ratio lambda = l/l0 = 5. The unstretched films were found to be moderately ordered, comprised of a component present at 80% with a Gaussian distribution of 60 degrees fwhm, while the remaining 20% is isotropically distributed. A distribution of 9 degrees +/- 3 degrees fwhm was measured by NMR in good agreement with IR dichroism measurements for the uniaxially cold-stretched films, establishing that a high degree of orientational order can be introduced by cold stretching PPV films. 相似文献