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排序方式: 共有150条查询结果,搜索用时 62 毫秒
91.
Formycin B influx studies have shown that P388 and L1210 mouse leukemia cells, mouse L929 cells, mouse RAW 309 Cr.1 cells, LK35.2 mouse B-cell hybridoma cells and cultured mouse peritoneal macrophages express both Na(+)-dependent, active and nonconcentrative, facilitated nucleoside transport systems. In the mouse cell lines, active transport represented only a minor nucleoside transport component and was detected only by measuring formycin B uptake in the presence of dipyridamole or nitrobenzylthioinosine, strong inhibitors of facilitated, but not of active, nucleoside transport. Inhibition of facilitated transport resulted in the concentrative accumulation of formycin B in cells expressing active nucleoside transport. Concentrative formycin B accumulation was abolished by treatment of the cells with gramicidin or absence of Na+ in the extracellular medium and strongly inhibited by ATP depletion or ouabain treatment. Mouse macrophages accumulated formycin B to 70-times the extracellular concentration in the absence of dipyridamole during 90 min of incubation at 37 degrees C. Thus active transport represents a major nucleoside transport system of these cells, similarly as previously reported for mouse spleen lymphocytes. In contrast to the various types of mouse cells, active formycin B transport was not detected in human HeLa cells, human H9, Jurkat and CEM T lymphoidal cells and pig spleen lymphocytes. These cells expressed only facilitated nucleoside transport with kinetic properties similar to those of the facilitated transporters of other mammalian cells. 相似文献
92.
Witting PK Song C Hsu K Hua S Parry SN Aran R Geczy C Freedman SB 《Free radical biology & medicine》2011,51(7):1390-1398
The acute-phase protein serum amyloid A (SAA) is elevated during inflammation and may be deposited in atheroma where it promotes atherosclerosis. We investigated the proatherogenic effects of SAA on the vascular endothelium and their regulation by high-density lipoprotein (HDL). Exposure of human aortic endothelial cells (HAEC) to SAA (0.25-25 μg/ml) decreased nitric oxide (•NO) synthesis/bioavailability, although the endothelial NO synthase monomer-to-dimer ratio was unaffected. SAA (10 μg/ml) stimulated a Ca2+ influx linked to apocynin-sensitive superoxide radical anion (O2•−) production. Gene expression for arginase-1, nuclear factor κB (NF-κB), interleukin-8, and tissue factor (TF) increased within 4 h of SAA stimulation. Enzymatically active Arg-1/2 was detected in HAEC cultured with SAA for 24 h. Therefore, in addition to modulating •NO bioavailability by stimulating O2•− production in the endothelium, SAA modulated vascular l-Arg bioavailability. SAA also diminished relaxation of preconstricted aortic rings induced by acetylcholine, and added superoxide dismutase restored the vascular response. Preincubation of HAEC with HDL (100 or 200, but not 50, μg/ml) before (not after) SAA treatment ameliorated the Ca2+ influx and O2•− production; decreased TF, NF-κB, and Arg-1 gene expression; and preserved overall vascular function. Thus, SAA may promote endothelial dysfunction by modulating •NO and l-Arg bioavailability, and HDL pretreatment may be protective. The relative HDL to SAA concentrations may regulate the proatherogenic properties of SAA on the vascular endothelium. 相似文献
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Ying Bai Lile Malania Danilo Alvarez Castillo David Moran Sumalee Boonmar Aran Chanlun Fanan Suksawat Soichi Maruyama Darryn Knobel Michael Kosoy 《PloS one》2013,8(11)
Bartonella bovis is commonly detected in cattle. One B. bovis strain was recently isolated from a cow with endocarditis in the USA, suggesting its role as an animal pathogen. In the present study, we investigated bartonella infections in 893 cattle from five countries (Kenya, Thailand, Japan, Georgia, and Guatemala) and 103 water buffaloes from Thailand to compare the prevalence of the infection among different regions and different bovid hosts. We developed a multi-locus sequence typing (MLST) scheme based on nine loci (16S rRNA, gltA, ftsZ, groEL, nuoG, ribC, rpoB, ssrA, and ITS) to compare genetic divergence of B. bovis strains, including 26 representatives from the present study and two previously described reference strains (one from French cows and another from a cow with endocarditis in the USA). Bartonella bacteria were cultured in 6.8% (7/103) of water buffaloes from Thailand; all were B. bovis. The prevalence of bartonella infections in cattle varied tremendously across the investigated regions. In Japan, Kenya, and the Mestia district of Georgia, cattle were free from the infection; in Thailand, Guatemala, and the Dusheti and Marneuli districts of Georgia, cattle were infected with prevalences of 10–90%. The Bartonella isolates from cattle belonged to three species: B. bovis (n=165), B. chomelii (n=9), and B. schoenbuchensis (n=1), with the latter two species found in Georgia only. MLST analysis suggested genetic variations among the 28 analyzed B. bovis strains, which fall into 3 lineages (I, II, and III). Lineages I and II were found in cattle while lineage III was restricted to water buffaloes. The majority of strains (17/28), together with the strain causing endocarditis in a cow in the USA, belonged to lineage I. Further investigations are needed to determine whether B. bovis causes disease in bovids. 相似文献
96.
Labrijn AF Rispens T Meesters J Rose RJ den Bleker TH Loverix S van den Bremer ET Neijssen J Vink T Lasters I Aalberse RC Heck AJ van de Winkel JG Schuurman J Parren PW 《Journal of immunology (Baltimore, Md. : 1950)》2011,187(6):3238-3246
A distinctive feature of human IgG4 is its ability to recombine half molecules (H chain and attached L chain) through a dynamic process termed Fab-arm exchange, which results in bispecific Abs. It is becoming evident that the process of Fab-arm exchange is conserved in several mammalian species, and thereby represents a mechanism that impacts humoral immunity more generally than previously thought. In humans, Fab-arm exchange has been attributed to the IgG4 core-hinge sequence (226-CPSCP-230) in combination with unknown determinants in the third constant H chain domain (CH3). In this study, we investigated the role of the CH3 domain in the mechanism of Fab-arm exchange, and thus identified amino acid position 409 as the critical CH3 determinant in human IgG, with R409 resulting in exchange and K409 resulting in stable IgG. Interestingly, studies with IgG from various species showed that Fab-arm exchange could not be assigned to a common CH3 domain amino acid motif. Accordingly, in rhesus monkeys (Macaca mulatta), aa 405 was identified as the CH3 determinant responsible (in combination with 226-CPACP-230). Using native mass spectrometry, we demonstrated that the ability to exchange Fab-arms correlated with the CH3-CH3 dissociation constant. Species-specific adaptations in the CH3 domain thus enable Fab-arm exchange by affecting the inter-CH3 domain interaction strength. The redistribution of Ag-binding domains between molecules may constitute a general immunological and evolutionary advantage. The current insights impact our view of humoral immunity and should furthermore be considered in the design and evaluation of Ab-based studies and therapeutics. 相似文献
97.
Martin Aran Clara Smal Leonardo Pellizza Mariana Gallo Lisandro H. Otero Sebastián Klinke Fernando A. Goldbaum Esteban R. Ithurralde Andrés Bercovich Walter P. Mac Cormack Adrián G. Turjanski Daniel O. Cicero 《Proteins》2014,82(11):3062-3078
The structure of the BA42 protein belonging to the Antarctic flavobacterium Bizionia argentinensis was determined by nuclear magnetic resonance and X‐ray crystallography. This is the first structure of a member of the PF04536 family comprised of a stand‐alone TPM domain. The structure reveals a new topological variant of the four β‐strands constituting the central β‐sheet of the αβα architecture and a double metal binding site stabilizing a pair of crossing loops, not observed in previous structures of proteins belonging to this family. BA42 shows differences in structure and dynamics in the presence or absence of bound metals. The affinity for divalent metal ions is close to that observed in proteins that modulate their activity as a function of metal concentration, anticipating a possible role for BA42. Proteins 2014; 82:3062–3078. © 2014 Wiley Periodicals, Inc. 相似文献
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Begoña Aran Ignasi Rodríguez-Pizà Ángel Raya Antonella Consiglio Yolanda Muñoz Pere N. Barri Juan Carlos Izpisúa Anna Veiga 《In vitro cellular & developmental biology. Animal》2010,46(3-4):356-366
We report here the legislative issues related to embryo research and human embryonic stem cell (hESC) research in Spain and the derivation of nine hESC lines at the Center of Regenerative Medicine in Barcelona. You can find the information for obtaining our lines for research purposes at blc@cmrb.eu. 相似文献
100.
Joeri Borstlap Mai X. Luong Heather M. Rooke B. Aran A. Damaschun A. Elstner Kelly P. Smith Gary S. Stein Anna Veiga 《In vitro cellular & developmental biology. Animal》2010,46(3-4):242-246
Rapid advances in stem cell research have led to the derivation of hundreds of human embryonic stem (hES) cell lines in centers throughout the world, as well as the development of new technologies for producing pluripotent stem cells. These cell lines have unique characteristics and were derived using a variety of ethical guidelines. Stem cell registries have been developed in order to collect, organize, and disseminate cell line-specific information. In this review, we describe the current state of the field by providing an overview of the unique qualities and mandates of the three major stem cell registries: the European hES Cell Registry, the Registry of hES Cell Line Provenance developed by the International Society for Stem Cell Research, and the International Stem Cell Registry of hES and induced pluripotent stem cell lines established at the University of Massachusetts Medical School. While each registry has its own unique mandate and features, there is some overlap in the goals and information provided. This review discusses the challenges and prospects for an integrated approach in which all three registries effectively collaborate to minimize duplication and facilitate information exchange within the stem cell community. 相似文献