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1.
Multiple cellular functions of urokinase and its receptor are associated with the receptor’s capability to interact with a number of ligands at the molecular level. The presence of urokinase is generally needed for the urokinase receptor to acquire this capability. Recent X-ray studies of the structure of the urokinase receptor in complex with either its ligand or peptide inhibitors demonstrate the flexibility of the domain organization of the receptor, suggesting that unliganded urokinase receptor may exist in a latent form that has a conformation different from its ligand-binding form. Received 22 November 2006; received after revision 8 January 2007; accepted 7 February 2007  相似文献   

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Zusammenfassung An Modellpräparaten wurde festgestellt, dass die Färbbarkeit der konjugierten Heparin-Histamin-Moleküle gleich ist wie die des Heparins selbst. Der fermentative Abbau des Heparins führt nicht zur vermehrten Freisetzung von Histamin.  相似文献   

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Zusammenfassung Vom ektodermalen Proctodaeum wächst ein kleiner Divertikel dem Vornierengang entgegen und vereinigt sich mit dessen kaudalem Ende. Einen weiteren Anteil hat das Proctodaeum an der Bildung des Vornierenganges nicht. Zugleich mit dem Proctodaeum invaginiert Material für den Mesonephros, das sich in Zellgruppen entlang dem hinteren Ende des Vornierenganges lagert.  相似文献   

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The exact cause of Alzheimer’s disease (AD) is still unknown, but the deposition of amyloid-β (Aβ) plaques and chronic inflammation indicates that immune disturbances are involved in AD pathogenesis. Recent genetic studies have revealed that many candidate genes are expressed in both microglia and myeloid cells which infiltrate into the AD brains. Invading myeloid cells controls the functions of resident microglia in pathological conditions, such as AD pathology. AD is a neurologic disease with inflammatory component where the immune system is not able to eliminate the perpetrator, while, concurrently, it should prevent neuronal injuries induced by inflammation. Recent studies have indicated that AD brains are an immunosuppressive microenvironment, e.g., microglial cells are hyporesponsive to Aβ deposits and anti-inflammatory cytokines enhance Aβ deposition. Immunosuppression is a common element in pathological disorders involving chronic inflammation. Studies on cancer-associated inflammation have demonstrated that myeloid-derived suppressor cells (MDSCs) have a crucial role in the immune escape of tumor cells. Immunosuppression is not limited to tumors, since MDSCs can be recruited into chronically inflamed tissues where inflammatory mediators enhance the proliferation and activation of MDSCs. AD brains express a range of chemokines and cytokines which could recruit and expand MDSCs in inflamed AD brains and thus generate an immunosuppressive microenvironment. Several neuroinflammatory disorders, e.g., the early phase of AD pathology, have been associated with an increase in the level of circulating MDSCs. We will elucidate the immunosuppressive armament of MDSCs and present evidences in support of the crucial role of MDSCs in the pathogenesis of AD.  相似文献   

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Five cell types recently isolated from the bovine corpus luteum differed in their epithelioid morphology and their cytoskeleton, but shared common criteria of microvascular endothelial cells1,2. To give strong evidence for the separate entity, the growth rate of the 5 phenotypically different cells was studied. They were seeded at low density on day 0. Most of these cells were treated with 200 to 1000 U recombinant bovine interferon- (IFN-) for 3 days. The untreated remainder served as controls. Cell counts were made for all cultures on days 4, 7, 10 and 13. morphology: 13 d after treatment with IFN- senescent cells as well as intact cells occurred in cultures of cell types 1 to 4. Cultures of cell type 5 were apparently unchanged and resembled their untreated counterparts. Desminpositive cells in cultures of cell type 2 developed cell processes. Growth rate: In the absence of IFN-, the growth rate was high for cell types 3 and 4, moderate for cell type 1, and low for cell types 2 and 5. The presence of IFN- caused anti-proliferative effects. These were higher for cell types 3 and 4 than for cell types 1 and 2. IFN- could be cytotoxic on cell type 3. In contrast, the cytokine tended to support the cell growth of cell type 5. These findings substantiate the postulate that endothelial cells exhibiting separate morphology in culture also function differently.  相似文献   

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The number of circulating mesenchymal stem cells (MSC), analyzed after acute myocardial infarction (AMI), was lower in AMI patients who developed heart failure (HF) in the follow-up. Conversely, the circulating levels of tumor necrosis factor (TNF)-α, and osteoprotegerin (OPG) were higher in AMI patients who developed HF with respect to the patients who did not develop HF. In vitro exposure to TNF-α enhanced the migration of MSC in response to TNF-related apoptosis-inducing ligand (TRAIL) and significantly increased the release of OPG by endothelial cells. On the contrary, OPG dose-dependently neutralized the in vitro pro-migratory activity of TRAIL. Thus, TNF-α exhibits opposite effects on MSC migration driven by TRAIL: it is capable of potentiating MSC migration as well as of inhibiting MSC migration as an indirect consequence of OPG induction, which might result in a suboptimal recruitment of circulating MSC after AMI in those patients who develop HF in the follow-up.  相似文献   

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Periodicity in predatory activity was observed in overwintered females ofTyphlodromus pyri Scheuten (Acari: Phytoseiidae). Chronobiometrical analysis revealed that an approximately circabiseptan (about-14-day) rhythm is statistically significant, with a striking depression around the full moon.  相似文献   

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Philosophers now commonly reject the value free ideal for science by arguing that non-epistemic values, including personal or social values, are permissible within the core of scientific research. However, little attention has been paid to the normative political consequences of this position. This paper explores these consequences and shows how political theory is fruitful for proceeding in a world without value-neutral science. I draw attention to an oft-overlooked argument employed by proponents of the value free ideal I dub the “political legitimacy argument.” This argument claims that the value-free ideal follows directly from the foundational principles of liberal democracy. If so, then the use of value-laden scientific information within democratic decision making would be illegitimate on purely political grounds. Despite highlighting this unaddressed and important argument, I show how it can be rejected. By appealing to deliberative democratic theory, I demonstrate scientific information can be value-laden and politically legitimate. The deliberative democratic account I develop is well suited for capturing the intuitions of many opponents of the value free ideal and points to a new set of questions for those interested in values in science.  相似文献   

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Résumé Il a été montré que l'appareil réticulaire classique de Golgi dans les cellules pancréatiques des amphibies et des mammifères est un produit artificiel. Un certain nombre de raisons sont proposées pour expliquer ce fait.  相似文献   

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Zusammenfassung Die angebliche Aufhebung der entzündungshemmenden Wirkung des Cortisons durch Thyreo-Parathyreoidektomie wurde experimentell nachgeprüft. Für die objektive Messung des Entzündungsgrades wurden drei Methoden benutzt: Die sogenannte «granuloma pouch» nach Krotonöl und die sogenannte «topical irritation arthritis» nach Formalin und Dextran.In allen drei Testen war es unmöglich, die entzündungshemmende Wirkung des Cortisons durch Thyreo-Parathyreoidektomie zu verhindern.  相似文献   

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Résumé L'auteur montre que l'appareil réticulaire classique de Golgi dans les cellules caliciformes intestinales des Vertébrés est un produit artificiel. Diverses raisons sont alléguées pour expliquer ce fait.  相似文献   

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Zusammenfassung Es wurde untersucht, ob die Biosynthese der Nukleinsäuren in wachsenden Systemen mit dem Abbau von ursprünglich vorhandenen Nukleinsäuren derselben Art gekoppelt ist. Die Versuche wurden mit Bakterien (E. coli) und mit Rattenleber gemacht. Die in der Zelle vorhandenen Nukleinsäuren waren mit P32 markiert, und es wurde der Verlust an Radioaktivität in jeder der beiden Nukleinsäuretypen im Laufe des Wachstums gemessen. Die Resultate wiesen darauf hin, dass das Auftreten von neuen Nukleinsäuremolekeln in der lebenden Zelle ohne den begleitenden Abbau der alten Molekeln stattfinden kann.

Supported in part by the Scientific Research Fund of the Ministry of Education given to the Synthetic Research Group on Nucleic Acids. The warm encouragement given to this work by Prof.J. Kamahora of this Institute is heartily acknowledged. We are further indebted to Dr.T. Miura, Department of Radiology, University of Osaka Medical School, for his help in this work.  相似文献   

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This paper analyzes the experiment presented in 2019 by the Event Horizon Telescope (EHT) Collaboration that unveiled the first image of the supermassive black hole at the center of galaxy M87. The intended aim of the paper is to assess whether the EHT Collaboration has made an “inference to the best explanation” (IBE) to conclude that the data effectively confirm the hypothesis that the object at the center of M87 is in fact a supermassive Kerr rotating black hole. I demonstrate that the EHT Collaboration has applied an IBE. It is shown that the hypothesis that at the center of M87 there is a supermassive Kerr rotating black hole was already the best explanation at the time in which the 2017 EHT experiment was conducted. My analysis is intertwined with considerations on realist and empiricist interpretations of IBE, which are used to assess whether the conclusion that the object at the center of M87 is a Kerr rotating black hole implies holding a realist commitment with respect to such object.  相似文献   

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Adenylate kinase activity of intact mitochondria is strongly inhibited by Ap5A, i.e. p1,p5-Di (adenosine-5') pentaphosphate, whereas oxidative phosphorylation is not affected. Therefore, Ap5A is a useful tool to distinguish between oxidative and non oxidative ATP generating reactions.  相似文献   

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