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排序方式: 共有130条查询结果,搜索用时 15 毫秒
1.
Summary Taurine transport was measured in cultured epithelial cells-LLC-PK1 and MDCK-grown on permeable membrane supports. Taurine transport by LLC-PK1 cells was greater on the apical surface compared to the basolateral surface. MDCK cells exhibited greater taurine uptake from the basolateral side. Transepithelial taurine flux was in the direction of apical to basolateral in the LLC-PK1 monolayers. There was no net transepithelial movement of taurine in the MDCK monolayers. Efflux of taurine from the apical and the basolateral membrane surfaces of LLC-PK1 cell monolayers was stimulated by external-alanine but not L-alanine. Efflux of taurine from MDCK cell monolayers was stimulated by-alanine on the basolateral surface. While the competitive inhibitor guainidinoeithane sulfonate (GES) competitively inhibited taurine uptake to a similar degree on the apical and basolateral surface of LLC-PK1 cell monolayers, GES had a more potent inhibitory effect on the basolateral taurine uptake in MDCK cells when compared to its inhibition of apical taurine transport. We conclude that there are characteristic differences in transport of taurine by apical and basolateral surfaces of LLC-PK1 and MDCK cells which may be the consequence of asymmetric distribution or unique structural properties of the taurine transporter.Supported by a grant from the National Institutes of Health (DK 37223), the American Heart Association (92-004470). 相似文献
2.
S. A. Everson J. W. Lynch M. A. Chesney G. A. Kaplan D. E. Goldberg S. B. Shade R. D. Cohen R. Salonen J. T. Salonen 《BMJ (Clinical research ed.)》1997,314(7080):553-558
OBJECTIVE: To examine the combined influence of workplace demands and changes in blood pressure induced by stress on the progression of carotid atherosclerosis. DESIGN: Population based follow up study of unestablished as well as traditional risk factors for carotid atherosclerosis, ischaemic heart disease, and other outcomes. SETTING: Eastern Finland. SUBJECTS: 591 men aged 42-60 who were fully employed at baseline and had complete data on the measures of carotid atherosclerosis, job demands, blood pressure reactivity, and covariates. MAIN OUTCOME MEASURES: Change in ultrasonographically assessed intima-media thickness of the right and left common carotid arteries from baseline to 4 year follow up. RESULTS: Significant interactions between workplace demands and stress induced reactivity were observed for all measures of progression (P < 0.04). Men with large changes in systolic blood pressure (20 mm Hg or greater) in anticipation of a maximal exercise test and with high job demands had 10-40% greater progression of mean (0.138 v 0.123 mm) and maximum (0.320 v 0.261 mm) intima-media thickness and plaque height (0.347 v 0.264) than men who were less reactive and had fewer job demands. Similar results were obtained after excluding men with prevalent ischaemic heart disease at baseline. Findings were strongest among men with at least 20% stenosis or non-stenotic plaque at baseline. In this subgroup reactive men with high job demands had more than 46% greater atherosclerotic progression than the others. Adjustment for atherosclerotic risk factors did not alter the results. CONCLUSIONS: Men who showed stress induced blood pressure reactivity and who reported high job demands experienced the greatest atherosclerotic progression, showing the association between dispositional risk characteristics and contextual determinants of disease and suggesting that behaviourally evoked cardiovascular reactivity may have a role in atherogenesis. 相似文献
3.
A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths 总被引:8,自引:2,他引:6
Cho S; Mitchell A; Regier JC; Mitter C; Poole RW; Friedlander TP; Zhao S 《Molecular biology and evolution》1995,12(4):650-656
Molecular systematists need increased access to nuclear genes. Highly
conserved, low copy number protein-encoding nuclear genes have attractive
features for phylogenetic inference but have heretofore been applied mostly
to very ancient divergences. By virtue of their synonymous substitutions,
such genes should contain a wealth of information about lower-level
taxonomic relationships as well, with the advantage that amino acid
conservatism makes both alignment and primer definition straightforward. We
tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene
in the noctuid moth subfamily Heliothinae, which has probably diversified
since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing
heliothine groupings strongly supported by previous morphological and
allozyme studies. The single most parsimonious gene tree and the
neighbor-joining tree for all nucleotides show almost complete concordance
with the morphological tree. Homoplasy and pairwise divergence levels are
low, transition/transversion ratios are high, and phylogenetic information
is spread evenly across gene regions. The EF-1 alpha gene and presumably
other highly conserved genes hold much promise for phylogenetics of
Tertiary age eukaryote groups.
相似文献
4.
A spectrophotometric assay for chlorine-containing compounds. 总被引:3,自引:0,他引:3
Determinations of hypochlorous acid and chloramine compounds are important in a number of areas. Several techniques are now available for such analyses, but most require unstable reagents and/or multiple steps in the analytical procedure. We have developed a simple, one-step spectrophotometric assay for reactive chlorine-containing compounds involving the oxidation of ascorbic acid by hypochlorous acid or chloramines. There is no interference from other nonhalide oxidants such as hydrogen peroxide or hypothiocyanous acid. Because small amounts of ascorbic acid will not damage biological materials, this method also allows continuous measurements of the generation of chlorine-containing compounds by activated neutrophils. This simple assay permits precise analysis of as little as 1 nmol of HOCl. 相似文献
5.
Cultured chick embryo fibroblasts derived from skin and skeletal muscle exhibit hyaluronidase activity both associated with the cell layer and secreted into the medium. Although both forms of the enzyme have a number of similar characteristics (R.W. Orkin and B.P. Toole, 1980, J. Biol. CHem. 255), they differ in thermal stability at neutral pH and in behavior on ion-exchange chromatography. Both forms of the enzyme are equally stable at acidic pH for long intervals, but the cell-associated hyaluronidase is significantly less stable than the secreted froms at neutral pH and at temperatures more than or equal to 30 degrees C. Neither the presence of proteases nor inhibitors of hyaluronidase appear to be involved in the cell-asspcoated enzyme. Chromatography of the two forms of hyaluronidase on carboxymethyl cellulose reveals that most (60-90 percent) of the secreted form of the enzyme elutes at a lower ionic strength than the cell- associated enzyme. Treatment of the secreted form of hyaluronidase with neuraminidase shifts its elution profile on carboxymethyl cellulose toward that of the cell-associated form, and also decreases its thermal stability at neutral pH. In contrast, treatment of the secreted form of hyaluronidase with alkaline phosphatase has no detectable effect. These data suggest that the secreted hyaluronidase differs from the cellular form in possessing additional sialic acid residues which endow the former with increased stability in the extracellular milieu. 相似文献
6.
Papagno L Spina CA Marchant A Salio M Rufer N Little S Dong T Chesney G Waters A Easterbrook P Dunbar PR Shepherd D Cerundolo V Emery V Griffiths P Conlon C McMichael AJ Richman DD Rowland-Jones SL Appay V 《PLoS biology》2004,2(2):E20
Progress in the fight against the HIV/AIDS epidemic is hindered by our failure to elucidate the precise reasons for the onset of immunodeficiency in HIV-1 infection. Increasing evidence suggests that elevated immune activation is associated with poor outcome in HIV-1 pathogenesis. However, the basis of this association remains unclear. Through ex vivo analysis of virus-specific CD8+ T-cells and the use of an in vitro model of naïve CD8+ T-cell priming, we show that the activation level and the differentiation state of T-cells are closely related. Acute HIV-1 infection induces massive activation of CD8+ T-cells, affecting many cell populations, not only those specific for HIV-1, which results in further differentiation of these cells. HIV disease progression correlates with increased proportions of highly differentiated CD8+ T-cells, which exhibit characteristics of replicative senescence and probably indicate a decline in T-cell competence of the infected person. The differentiation of CD8+ and CD4+ T-cells towards a state of replicative senescence is a natural process. It can be driven by excessive levels of immune stimulation. This may be part of the mechanism through which HIV-1-mediated immune activation exhausts the capacity of the immune system. 相似文献
7.
Enantiomerically pure compounds as precursors for the synthesis of hydroxylated derivatives of artemisinin/arteether have been prepared from (+)-(S)-carvone and (+)-car-2-ene. 相似文献
8.
The invasive freshwater snail Tarebia granifera (Lamarck, 1822) was first reported in South Africa in 1999 and it has become widespread across the country, with some evidence to suggest that it reduces benthic macroinvertebrate biodiversity. The current study aimed to identify the primary abiotic drivers behind abundance patterns of T. granifera, by comparing the current abundance of the snail in three different regions, and at three depths, of the highly modified Nseleni River in KwaZulu-Natal, South Africa. Tarebia granifera was well established throughout the Nseleni River system, with an overall preference for shallow waters and seasonal temporal patterns of abundance. Although it is uncertain what the ecological impacts of the snail in this system are, its high abundances suggest that it should be controlled where possible and prevented from invading other systems in the region. 相似文献
9.
A PBX1 transcriptional network controls dopaminergic neuron development and is impaired in Parkinson's disease
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J Carlos Villaescusa Bingsi Li Enrique M Toledo Pia Rivetti di Val Cervo Shanzheng Yang Simon RW Stott Karol Kaiser Saiful Islam Daniel Gyllborg Rocio Laguna‐Goya Michael Landreh Peter Lönnerberg Anna Falk Tomas Bergman Roger A Barker Sten Linnarsson Licia Selleri Ernest Arenas 《The EMBO journal》2016,35(18):1963-1978
10.
Taurine participates in a number of different physiologic and biologic processes in the kidney, often reflected by urinary excretion patterns. The kidney is key to aspects of taurine body pool size and homeostasis. This review will examine the renal-taurine interactions relative to ion reabsorption; renal blood flow and renal vascular endothelial function; antioxidant properties, especially in the glomerulus; and the role of taurine in ischemia and reperfusion injury. In addition, taurine plays a role in the renal cell cycle and apoptosis, and functions as an osmolyte during the stress response. The role of the kidney in adaptation to variations in dietary taurine intake and the regulation of taurine body pool size are described. Finally, the protective function of taurine against several kidney diseases is reviewed. 相似文献