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排序方式: 共有130条查询结果,搜索用时 265 毫秒
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Suwalsky M Schneider C Norris B Villena F Cárdenas H Cuevas F Sotomayor CP 《Zeitschrift für Naturforschung. C, Journal of biosciences》2002,57(9-10):930-938
Experimental results indicate a significant decrease in the potential difference (PD) and in the short-circuit current (Isc) after the application of proparacaine to isolated toad skin, which may reflect an inhibition of the active transport of ions. This finding was explained on the basis of the results obtained from membrane models incubated with proparacaine. These consisted of human erythrocytes, isolated unsealed human erythrocyte membranes (IUM), phospholipid multilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representatives of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively, and in large unilamellar vesicles (LUV) of DMPC X-ray diffraction showed that proparacaine interaction with DMPC and DMPE bilayers perturbed both structures, especially DMPC. This result, confirmed by fluorescence spectroscopy of DMPC LUV at 18 degrees C, demonstrated that the local anesthetic (LA) could interact with the lipid moiety of cell membranes. However, effects observed by scanning electron microscopy (SEM) of human erythrocytes and by fluorescence spectroscopy of IUM might also imply proparacaine-protein interactions. Thus, the LA may alter epitheial sodium channels through interaction with the lipid matrix and with channel protein residues. 相似文献
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Summary A polymorphic restriction site has been found in intron 11 of the gene for glucose-6-phosphate dehydrogenase (G6PD). This site is produced by a TC substitution 13 bp upstream of exon 12, producing an NlaIII restriction site. In various populations there was a strong association between a T at nt 1311 of the G6PD cDNA and the presence of the NlaIII restriction site. Among African Americans, however, the presence of a C at nt 1311 was sometimes associated with the presence of a polymorphic NlaIII site. 相似文献
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Suwalsky M Rivera C Norris B Cárdenas H 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2007,146(1-2):138-146
Arsenic, applied as sodium arsenite (As(III)) to either inner or outer surfaces of the isolated toad skin, dose-dependently decreased the short-circuit current (Isc), potential difference (PD) and sodium conductance (G(Na)) in the concentration range 1-1000 microM, with effects often lasting over 3 h. Maximal inhibitory effect was over 90% with an IC(50) of about 34 microM. Applied during amiloride block, As(III) did not change this effect. However, an increase in electric parameters was noted during the initial 30 min in 22 experiments, indicating a possible translocation of cytosolic protein kinase C (PKC) to the membrane within 15 min, thus stimulating sodium transport; this is followed by a progressive inhibition of kinase activity. Comparative effects of amiloride (8 microM), As(III) (100 microM, outer surface) and noradrenaline (NA, 10 microM, inner surface) showed a significant increase in the stimulatory effect of NA on the electric parameters, which could be the result of arsenite clustering of cell surface receptors and activation of ensuing cellular signal transduction pathways. Ouabain 5 microM, followed by As(III) 100 microM, also stimulated the skin response to NA (10 microM), although the duration of the two phases of the response was markedly shortened. The exact mechanism is still in doubt: however, As(III) increases cerebral metabolites of NA and ouabain can increase NA efflux from tissue slices. The amiloride test, performed with As(III) in the outer surface, confirmed significant decrease in all the parameters: the driving force (E(Na)), sodium conductance (G(Na)), and importantly, shunt conductance (G(sh)), due to the known fact that arsenic inhibits gap junctional intercellular communication. 相似文献
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The sunflower genus, Helianthus, is recognized widely for the cultivated sunflower H. annuus and scientifically as a model organism for studying diploid and polyploid hybrid speciation, introgression, and genetic architecture. A resolved phylogeny for the genus is essential for the advancement of these scientific areas. In the past, phylogenetic relationships of the perennial species and polyploid hybrids have been particularly difficult to resolve. Using the external transcribed spacer region of the nuclear 18S-26S rDNA region, we reveal for the first time a highly resolved gene tree for Helianthus. Phylogenetic analysis allowed the determination of a monophyletic annual H. sect. Helianthus, a two-lineage polyphyletic H. sect. Ciliares, and the monotypic H. sect. Agrestis, all of which were nested within a large perennial and polyphyletic H. sect. Divaricati. The distribution of perennial polyploids and known annual diploid hybrids on this phylogeny suggested multiple independent hybrid speciation events that gave rise to at least four polyploids and three diploid hybrids. Also provided by this phylogeny was evidence for homoploid hybrid speciation outside H. sect. Helianthus. Finally, previous hypotheses about the secondary chemistry in the genus were tested in a phylogenetic framework to obtain a better understanding of the evolution of these compounds in Helianthus. 相似文献
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Hong-Van Tieu Ting-Yuan Liu Sophia Hussen Matthew Connor Lei Wang Susan Buchbinder Leo Wilton Pamina Gorbach Kenneth Mayer Sam Griffith Corey Kelly Vanessa Elharrar Gregory Phillips Vanessa Cummings Beryl Koblin Carl Latkin HPTN 《PloS one》2015,10(8)