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排序方式: 共有142条查询结果,搜索用时 15 毫秒
91.
92.
Roell W Lewalter T Sasse P Tallini YN Choi BR Breitbach M Doran R Becher UM Hwang SM Bostani T von Maltzahn J Hofmann A Reining S Eiberger B Gabris B Pfeifer A Welz A Willecke K Salama G Schrickel JW Kotlikoff MI Fleischmann BK 《Nature》2007,450(7171):819-824
Ventricular tachyarrhythmias are the main cause of sudden death in patients after myocardial infarction. Here we show that transplantation of embryonic cardiomyocytes (eCMs) in myocardial infarcts protects against the induction of ventricular tachycardia (VT) in mice. Engraftment of eCMs, but not skeletal myoblasts (SMs), bone marrow cells or cardiac myofibroblasts, markedly decreased the incidence of VT induced by in vivo pacing. eCM engraftment results in improved electrical coupling between the surrounding myocardium and the infarct region, and Ca2+ signals from engrafted eCMs expressing a genetically encoded Ca2+ indicator could be entrained during sinoatrial cardiac activation in vivo. eCM grafts also increased conduction velocity and decreased the incidence of conduction block within the infarct. VT protection is critically dependent on expression of the gap-junction protein connexin 43 (Cx43; also known as Gja1): SMs genetically engineered to express Cx43 conferred a similar protection to that of eCMs against induced VT. Thus, engraftment of Cx43-expressing myocytes has the potential to reduce life-threatening post-infarct arrhythmias through the augmentation of intercellular coupling, suggesting autologous strategies for cardiac cell-based therapy. 相似文献
93.
1A6/DRIM has been identified as UTP20, a small subunit processome component, functioning in 18S rRNA processing. In the present study, the maturation of 28S rRNA and 5.8S rRNA was inhibited when 1A6/DRIM was silenced in HeLa cells; and coin-cidently, an accumulation of 32S rRNA precursor was observed. Immunoprecipitation was performed with the anti-1A6/DRIM antibody, followed by Northern blot with the ITS2 probe. The results showed that 1A6/DRIM was associated with both 32S and 12S rRNA precursors in vivo. The expression profile of 1A6/DRIM during rRNA processing was investigated by sucrose density gradient fractionation in combination with Western blot analysis. The results demonstrated that 1A6/DRIM was involved in the pre-60S particles in addition to the pre-40S particles and co-sediment with the 32S and 12S rRNA precursors in the nucleolus. Furthermore, the interaction of U8 snoRNA with 1A6/DRIM was revealed by immunoprecipitation. These results demonstrated that 1A6/DRIM interacted with both 32S rRNA and U8 snoRNA, being involved in 28S rRNA and 5.8S rRNA processing. 相似文献
94.
Werner Ulrich 《Systemic Practice and Action Research》1993,6(6):583-611
We probably have simplified matters too much. We tend to talk about systems thinking and practice as if we knew what they are. The fashionable call for “holistic” or “systems” thinking in ecological issues provides a major example. This much is certain: the quest for comprehensiveness, although it represents an epistemologically necessary idea, is not realizable. If we assume that it is realizable, the critical idea underlying the quest will be perverted into its opposite, i.e., into a false pretension to superior knowledge and understanding—a danger of which the environmental movement does not always appear to be sufficiently aware. My question, therefore, is this: How can we deal critically with the fact that our thinking, and hence our knowledge, designs, and actions, cannot possibly be comprehensive, in the sense that we never “comprehend” all that ought to be understood before we pass to judgment and action? What consequences does this fact imply for a critical systems approach to ecological concerns and, ultimately, for our concepts of rationality in general? 相似文献
95.
An improved method for the collection of large numbers of inseminated eggs ofDrosophila melanogaster
F. E. Würgler H. Ulrich H. W. Spring 《Cellular and molecular life sciences : CMLS》1968,24(10):1082-1083
Zusammenfassung Es wird eine verbesserte Methode beschrieben, mit der innerhalb einer Sammelperiode von 3 min etwa 50-100 frisch besamte Eier vonDrosophila melanogaster gewonnen werden können. Verglichen mit den bisher üblichen Sammelperioden von 10, 30 oder mehr min erhält man wesentlich stadienhomogenere Gelege. Eine weitere Verkürzung der Sammelperiode unter 3 min ist wegen der stark abnehmenden Anzahl Eier je Gelege nicht möglich. Vorausgesetzt, dass alle Störungen der Fliegen durch Erschütterungen, Licht, Temperaturschwankungen usw ausgeschaltet werden, können z.B. für strahlenbiologische Experimente zahlreiche 3-min-Gelege im Laufe von 6 oder mehr Stunden gewonnen werden.
Work supported by Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung and Jubiläumsfond 1930 der ETH. 相似文献
Work supported by Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung and Jubiläumsfond 1930 der ETH. 相似文献
96.
97.
Yan Ma Rui Zheng Ziyuan Gao Ulrich Krupp Hai-wen Luo Wenwen Song Wolfgang Bleck 《矿物冶金与材料学报》2021,28(5):847-853
Medium-Mn steels have attracted immense attention for automotive applications owing to their outstanding combination of high strength and superior ductility. This steel class is generally characterized by an ultrafine-grained duplex microstructure consisting of ferrite and a large amount of austenite. Such a unique microstructure is processed by intercritical annealing, where austenite reversion occurs in a fine martensitic matrix. In the present study, austenite reversion in a medium-Mn alloy was simulated by the multiphase-field approach using the commercial software MICRESS? coupled with the thermodynamic database TCFE8 and the kinetic database MOBFE2. In particular, a faceted anisotropy model was incorporated to replicate the lamellar morphology of reversed austenite. The simulated microstructural morphology and phase transformation kinetics (indicated by the amount of phase) concurred well with experimental observations by scanning electron microscopy and in situ synchrotron high-energy X-ray diffraction, respectively. 相似文献
98.
Monoclonal antibodies show that neurofibrillary tangles and neurofilaments share antigenic determinants 总被引:49,自引:0,他引:49
B H Anderton D Breinburg M J Downes P J Green B E Tomlinson J Ulrich J N Wood J Kahn 《Nature》1982,298(5869):84-86
99.
U. Maschwitz S. Lenz A. Buschinger 《Cellular and molecular life sciences : CMLS》1986,42(10):1173-1174
Summary
Leptothorax affinis lays chemical trails during nest emigration. Workers which carried colony members during nest movement refused trails of nest mates and searched for their own trails. The origin of the individual specific trail substance could not be localized. 相似文献
100.
Conclusions The total proton load found in these ecosystems exceeds by far the known rates of buffering in soils by silicate weathering and release of basic cations (see above).Under the present proton load most forest soils will therefore acidify and besides losses of nutrients the occurrence of possible toxic ions in the soil unavoidable (Al-buffer range)20, 21.The proportion of the total proton load of the soil that is represented by the internal production emphasizes the importance of acid deposition as main cause of soil acidification and destabilization of forest ecosystems under Central European conditions. 相似文献