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排序方式: 共有539条查询结果,搜索用时 31 毫秒
31.
Susann Reinbothe Anna-Maria Larsson Marica Vaapil Caroline Wigerup Jianmin Sun Annika Jögi Drorit Neumann Lars Rönnstrand Sven Påhlman 《Biochemical and biophysical research communications》2014
The main function of Erythropoietin (EPO) and its receptor (EPOR) is the stimulation of erythropoiesis. Recombinant human EPO (rhEPO) is therefore used to treat anemia in cancer patients. However, clinical trials have indicated that rhEPO treatment might promote tumor progression and has a negative effect on patient survival. In addition, EPOR expression has been detected in several cancer forms. Using a newly produced anti-EPOR antibody that reliably detects the full-length isoform of the EPOR we show that breast cancer tissue and cells express the EPOR protein. rhEPO stimulation of cultured EPOR expressing breast cancer cells did not result in increased proliferation, overt activation of EPOR (receptor phosphorylation) or a consistent activation of canonical EPOR signaling pathway mediators such as JAK2, STAT3, STAT5, or AKT. However, EPOR knockdown experiments suggested functional EPO receptors in estrogen receptor positive (ERα+) breast cancer cells, as reduced EPOR expression resulted in decreased proliferation. This effect on proliferation was not seen in ERα negative cells. EPOR knockdown decreased ERα activity further supports a mechanism by which EPOR affects proliferation via ERα-mediated mechanisms. We show that EPOR protein is expressed in breast cancer cells, where it appears to promote proliferation by an EPO-independent mechanism in ERα expressing breast cancer cells. 相似文献
32.
Terminal deoxynucleotidyl transferase (TdT) contributes to the junctional diversity of immunoglobulin and T-cell receptors
by incorporating nucleotides in a template-independent manner. A closely related enzyme, polymerase μ (polμ), a template-directed
polymerase, plays a role in general end-joining double-strand break repair. We cloned zebrafish TdT and polμ and found them
to be 43% identical in amino acid sequence. Comparisons with sequences of other species revealed conserved residues typical
for TdT in the zebrafish sequence that support the template independence of this enzyme. Some but not all of these features
were identified in zebrafish polμ. In adult fish, TdT expression was most prominent in thymus, pro- and mesonephros, the primary
lymphoid organs in teleost fish and in spleen, intestine, and the tissue around the intestine. Polμ expression was detected
not only in pro- and mesonephros, the major sites for B-lymphocyte development, but also in ovary and testis and in all tissue
preparations to a low extent. TdT expression starts at 4 dpf and increases thereafter. Polμ is expressed at all times to a
similar extent. In situ studies showed a strong expression of TdT and polμ in the thymic cortex of 8-week-old fish. The characterization
of zebrafish TdT and polμ provide new insights in fish lymphopoiesis and addresses the importance and evolution of TdT and
polμ themselves. 相似文献
33.
Bullen JW Bluher S Kelesidis T Mantzoros CS 《American journal of physiology. Endocrinology and metabolism》2007,292(4):E1079-E1086
Adiponectin and its receptors play an important role in energy homeostasis and insulin resistance, but their regulation remains to be fully elucidated. We hypothesized that high-fat diet would decrease adiponectin but increase adiponectin receptor (AdipoR1 and AdipoR2) expression in diet-induced obesity (DIO)-prone C57BL/6J and DIO-resistant A/J mice. We found that circulating adiponectin and adiponectin expression in white adipose tissue are higher at baseline in C57BL/6J mice compared with A/J mice. Circulating adiponectin increases at 10 wk but decreases at 18 wk in response to advancing age and high-fat feeding. However, adiponectin levels corrected for visceral fat mass and adiponectin mRNA expression in WAT are affected by high-fat feeding only, with both being decreased after 10 wk in C57BL/6J mice. Muscle AdipoR1 expression in both C57BL/6J and A/J mice and liver adipoR1 expression in C57BL/6J mice increase at 18 wk of age. High-fat feeding increases both AdipoR1 and AdipoR2 expression in liver in both strains of mice and increases muscle AdipoR1 expression in C57BL/6J mice after 18 wk. Thus advanced age and high-fat feeding, both of which are factors that predispose humans to obesity and insulin resistance, are associated with decreasing adiponectin and increasing AdipoR1 and/or AdipoR2 levels. 相似文献
34.
Global analysis of nitrogen and phosphorus limitation of primary producers in freshwater, marine and terrestrial ecosystems 总被引:47,自引:1,他引:46
Elser JJ Bracken ME Cleland EE Gruner DS Harpole WS Hillebrand H Ngai JT Seabloom EW Shurin JB Smith JE 《Ecology letters》2007,10(12):1135-1142
The cycles of the key nutrient elements nitrogen (N) and phosphorus (P) have been massively altered by anthropogenic activities. Thus, it is essential to understand how photosynthetic production across diverse ecosystems is, or is not, limited by N and P. Via a large-scale meta-analysis of experimental enrichments, we show that P limitation is equally strong across these major habitats and that N and P limitation are equivalent within both terrestrial and freshwater systems. Furthermore, simultaneous N and P enrichment produces strongly positive synergistic responses in all three environments. Thus, contrary to some prevailing paradigms, freshwater, marine and terrestrial ecosystems are surprisingly similar in terms of N and P limitation. 相似文献
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37.
Shedding light on host niches: label‐free in situ detection of Mycobacterium gordonae via carotenoids in macrophages by Raman microspectroscopy
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Anja Silge Elias Abdou Kilian Schneider Susann Meisel Thomas Bocklitz Hui‐Wen Lu‐Walther Rainer Heintzmann Petra Rösch Jürgen Popp 《Cellular microbiology》2015,17(6):832-842
Macrophages are the primary habitat of pathogenic mycobacteria during infections. Current research about the host–pathogen interaction on the cellular level is still going on. The present study proves the potential of Raman microspectroscopy as a label‐free and non‐invasive method to investigate intracellular mycobacteria in situ. Therefore, macrophages were infected with Mycobacterium gordonae, a mycobacterium known to cause inflammation linked to intracellular survival in macrophages. Here, we show that Raman maps provided spatial and spectral information about the position of bacteria within determined cell margins of macrophages in two‐dimensional scans and in three‐dimensional image stacks. Simultaneously, the relative intracellular concentration and distributions of cellular constituents such as DNA, proteins and lipids provided phenotypic information about the infected macrophages. Locations of bacteria outside or close to the outer membrane of the macrophages were notably different in their spectral pattern compared with intracellular once. Furthermore, accumulations of bacteria inside of macrophages exhibit distinct spectral/molecular information because of the chemical composition of the intracellular microenvironment. The data show that the connection of microscopically and chemically gained information provided by Raman microspectroscopy offers a new analytical way to detect and to characterize the mycobacterial infection of macrophages. 相似文献
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39.
The binding of ofloxacin (OFLX) to human serum albumin (HSA) was investigated by fluorescence and circular dichroism (CD) techniques. The binding parameters have been evaluated by a fluorescence quenching method. Competitive binding measurements were performed in the presence of warfarin and ibuprofen and suggest binding to the warfarin site I of HSA. The distance r between donor (HSA) and acceptor (OFLX) was estimated according to the Forster's theory of non‐radiatiative energy transfer. CD spectra revealed that the binding of OFLX to HSA induced conformational changes in HSA. Molecular docking was performed and shows that for the lowest energy complex OFLX is located in site I of HSA, which correlate to the competitive binding experiments. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
40.
Windholz J Kovacs P Tönjes A Dittrich K Blüher S Kiess W Stumvoll M Körner A 《PloS one》2011,6(7):e22101