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91.
Effect of headgroup structure on catonic lipid-mediated transfection was investigated with either a (i) tertiary amine, (ii) quaternary amine with a hydroxyl, or (iii) quaternary amine with mesylate as headgroups. Liposomes were formulated using cholesterol or dioleoyl phosphatidyl ethanolamine (DOPE) as colipids, and transfection efficiencies were determined in rapidly dividing colon carcinoma (CT 26) and rat aortic smooth muscle (RASM) cells as well as in nondividing human pancreatic islets using luciferase and green fluorescent protein expression plasmids, pcDNA3-Luc and pCMS-EGFP, respectively. Liposome/pDNA complexes were evaluated for DNA conformational state by circular dichroism (CD), DNA condensation by electrophoretic mobility shift assay (EMSA), particle size and zeta potential by laser diffraction technique, and surface morphology by transmission electron microscopy (TEM). Encouraging transfection results were obtained with the mesylate headgroup based lipid in liposome formulations with DOPE as a colipid, which were higher than the commercially available Lipofectamine formulation. We hypothesize that the additional hydrogen bonding or covalent interactions of the headgroup with the plasmid DNA, leading to higher binding affinity of the cationic lipids to pDNA, results in higher transfection. This hypothesis is supported by TEM observations where elongated complexes were observed and more lipid was seen associated with the DNA. 相似文献
92.
For the identification of regulators of G-protein signaling (RGS) modulators, previously, we developed a luciferase based yeast pheromone response (YPhR) assay to functionally investigate RGS4 (K.H. Young, Y. Wang, C. Bender, S. Ajit, F. Ramirez, A. Gilbert, B.W. Nieuwenhuijsen, in: D.P. Siderovski (Ed.), Meth. Enzymol. 389 Regulators of G_protein Signaling, Part A, 2004.). To extend the diversity of this assay, additional RGS proteins were evaluated for functional complementation in a RGS (sst2Delta) knockout yeast strain. For RGS proteins that did not function in their native form, a series of chimeric constructs were generated with the N terminus of RGS4 fused in frame with the partial or full-length RGS cDNA of interest. RGS4 N terminus fused to either full-length or the C terminus of RGS7 successfully complemented sst2Delta. On the contrary, the RGS7N/RGS4C chimera (N terminus of RGS7 in frame with RGS domain of RGS4) was not effective, showing that N terminus of RGS4 helps in targeting. RGS10 exists as two splice variants, differing only by 8 amino acids (aa) in the N terminus, being either 168 aa (RGS10S), or 174 aa (RGS10). While RGS10 was functional in yeast, RGS10S required the presence of the N terminus of RGS4 for its activity. Although the same RGS4 N terminus domain was present in chimeras generated, the GTPase accelerating protein (GAP) function observed was not similar, suggesting differences in the RGS domain function. In conclusion, the use of RGS4 N terminus chimeric constructs enabled us to develop a selectivity assay for different RGS proteins. 相似文献
93.
Erik?Sahai Jeffrey?WyckoffEmail author Ulrike?Philippar Jeffrey?E?Segall Frank?Gertler John?Condeelis 《BMC biotechnology》2005,5(1):14
Background
The development of multiphoton laser scanning microscopy has greatly facilitated the imaging of living tissues. However, the use of genetically encoded fluorescent proteins to distinguish different cell types in living animals has not been described at single cell resolution using multiphoton microscopy. 相似文献94.
Wu M El-Kattan Y Lin TH Ghosh A Kumar VS Kotian PL Cheng X Bantia S Babu YS Chand P 《Nucleosides, nucleotides & nucleic acids》2005,24(10-12):1569-1585
Various C-1'-substituted acyclic N9 adenine nucleosides were prepared from 9-[(1-hydroxymethyl)(3-monomethoxytrityloxy)propyl]-N6-monomethoxytrityladenine. The hydroxymethyl was modified to the phosphonomethoxy derivative, and the 3-monomethoxytrityloxy was converted to hydroxyl, methoxy, azido, and amino. Other substituents, such as ethyl and ea-hydroxyethyl were also prepared. The resulting phosphonomethoxy derivatives were converted to prodrugs. 相似文献
95.
Sherameti I Shahollari B Venus Y Altschmied L Varma A Oelmüller R 《The Journal of biological chemistry》2005,280(28):26241-26247
96.
OBJECTIVE: To compare cervicovaginal smears obtained by a cotton-tipped swab with those obtained by cervix brush and modified Ayre spatula. STUDY DESIGN: A combined cervicovaginal smear was collected from 100 women using 3 different collection devices: cotton-tipped swab, cervix brush, and modified Ayre spatula. In each patient a set of 3 smears was collected by the same cytotechnologist using all 3 devices in random order. Smears were evaluated using parameters mandatory for an optimal smear: evenly dispersed, well-preserved, adequate cells from the transformation zone. The cost and availability of the collection devices were also considered. RESULTS: The swab was the most effective device in obtaining thin, evenly spread, adequate, well-preserved smears as against the cervix brush and Ayre spatula. The pickup of abnormal cells was similar with the cotton-tipped swab and cervix brush, while the Ayre spatula failed to yield high grade squamous intraepithelial lesions, atypical glandular cells of undetermined significance and adenocarcinoma cells. The cotton-tipped swab proved to be the most cost effective. CONCLUSION: A properly prepared cotton-tipped swab is an inexpensive, readily available, nontraumatic collection device that yields smear of optimal quality. 相似文献
97.
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99.
Present study provides an easy and efficient protocol for large scale clonal propagation of Coleus forskohlii, a threatened medicinal plant of commercial importance. Basal leaf lamina excised from upper three nodes of shoot was used as explant and its size, position, orientation and season of collection were initially optimized to select the most responsive explant condition. Enhanced shoot production and proliferation has been achieved on medium containing 2 μM BA + 0.1 μM NAA wherein, a highest number of 35 shoots/explant were produced. The regenerated shoots of varied length (3–5 cm) were transferred to root induction medium comprising of IBA, NAA and IAA (1–5 μM) in half-strength MS medium to determine the most suitable shoot length for proper root induction. Rooted plantlets were acclimatized in field conditions after proper hardening. Histological analysis was also carried out to confirm the nature of origin of shoot buds from leaf explants. 相似文献
100.
Gohil VM Agrawal SK Saxena AK Garg D Gopimohan C Bhutani KK 《Indian journal of experimental biology》2010,48(3):265-268
Aryl hydrazine and hydrazide analogues were synthesized based on p-tolyl hydrazine, isolated as a breakdown product of a secondary metabolite from the mushroom, Agaricus bisporus, and tested to be highly active molecule than 5-fluorouracil in in vitro anticancer studies. The synthesized analogues were tested for anticancer activity using NCI protocol. Anolgues 12 and 15 emerged as molecules with significant in vitro anticancer activity. Molecular docking study revealed the binding orientations of aryl hydrazines and hydrazides analogues in the active sites of thymidylate synthase. 相似文献