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排序方式: 共有230条查询结果,搜索用时 281 毫秒
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Zusammenfassung Cholesterin lässt sich als Bestandteil des ungereinigten Rh-Haptens nachweisen. Deshalb wurde geprüft, ob die perorale Aufnahme dieser Fraktion den Blutcholesterinspiegel beeinflusst. Bei 17 Menschen, die kein Hapten erhielten, und bei 61 Hapten-Empfangenden wurde keine Erhöhung des Cholesterinspiegels festgestellt. 相似文献
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The endodermal epithelium of vertebrates generates many types of enteroendocrine cells, including the insulin- and glucagon-secreting cells of the islets of Langerhans. Two studies disclose that Notch signalling controls which cells differentiate as enteroendocrine cells-a finding with implications for therapeutic strategy. 相似文献
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Betaglycan binds inhibin and can mediate functional antagonism of activin signalling 总被引:12,自引:0,他引:12
Lewis KA Gray PC Blount AL MacConell LA Wiater E Bilezikjian LM Vale W 《Nature》2000,404(6776):411-414
Activins and inhibins, structurally related members of the TGF-beta superfamily of growth and differentiation factors, are mutually antagonistic regulators of reproductive and other functions. Activins bind specific type II receptor serine kinases (ActRII or IIB) to promote the recruitment and phosphorylation of the type I receptor serine kinase, ALK4 (refs 7-9), which then regulates gene expression by activating Smad proteins. Inhibins also bind type II activin receptors but do not recruit ALK4, providing a competitive model for the antagonism of activin by inhibin. Inhibins fail to antagonize activin in some tissues and cells, however, suggesting that additional components are required for inhibin action. Here we show that the type III TGF-beta receptor, betaglycan, can function as an inhibin co-receptor with ActRII. Betaglycan binds inhibin with high affinity and enhances binding in cells co-expressing ActRII and betaglycan. Inhibin also forms crosslinked complexes with both recombinant and endogenously expressed betaglycan and ActRII. Finally, betaglycan confers inhibin sensitivity to cell lines that otherwise respond poorly to this hormone. The ability of betaglycan to facilitate inhibin antagonism of activin provides a variation on the emerging roles of proteoglycans as co-receptors modulating ligand-receptor sensitivity, selectivity and function. 相似文献
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In vertebrates with mutations in the Notch cell-cell communication pathway, segmentation fails: the boundaries demarcating somites, the segments of the embryonic body axis, are absent or irregular. This phenotype has prompted many investigations, but the role of Notch signalling in somitogenesis remains mysterious. Somite patterning is thought to be governed by a "clock-and-wavefront" mechanism: a biochemical oscillator (the segmentation clock) operates in the cells of the presomitic mesoderm, the immature tissue from which the somites are sequentially produced, and a wavefront of maturation sweeps back through this tissue, arresting oscillation and initiating somite differentiation. Cells arrested in different phases of their cycle express different genes, defining the spatially periodic pattern of somites and controlling the physical process of segmentation. Notch signalling, one might think, must be necessary for oscillation, or to organize subsequent events that create the somite boundaries. Here we analyse a set of zebrafish mutants and arrive at a different interpretation: the essential function of Notch signalling in somite segmentation is to keep the oscillations of neighbouring presomitic mesoderm cells synchronized. 相似文献
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Dominant negative mutations in human PPARgamma associated with severe insulin resistance, diabetes mellitus and hypertension 总被引:22,自引:0,他引:22
Barroso I Gurnell M Crowley VE Agostini M Schwabe JW Soos MA Maslen GL Williams TD Lewis H Schafer AJ Chatterjee VK O'Rahilly S 《Nature》1999,402(6764):880-883
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