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881.
Daniela Daga-Gordini Giorgio M. Bressan Ines Castellani Dino Volpin 《The Histochemical journal》1987,19(12):623-632
Summary Affinity-purified antitropoelastin antibodies have been used to localize tropoelastin-derived components in aortas from chick embryos of different age by immunoelectron microscopy. Staining in the matrix is first noted at day 3 associated with irregular bundles of filaments resembling microfibrils, in the absence of amorphous elastin deposits. Amorphous material, which rapidly accumulates at later stages, is heavily labelled, while surrounding microfibrils are only poorly labelled. By contrast, a more intense staining of microfibrils persists in regions in which amorphous material is not morphologically evident. These observations indicate that the initial accumulation of elastin requires microfibrils, while the two components are not in close association in the subsequent growth of the amorphous core of the fibre. Intracellular staining is evident in the secretory apparatus of the cell and in peripheral large vesicles. Differentiated cells also show regions of close contact with elastic fibres in which immunological staining for elastin is very close to the cell membrane. 相似文献
882.
Okamura Y Schmidt R Raschke I Hintze M Takeoka S Egner A Lang T 《Biophysical journal》2011,(8):1855-1863
Eukaryotic cells respond to signaling molecules with picomolar to nanomolar sensitivities. However, molar concentrations give no suggestion of the sufficient number of molecules per cell and are confusing when referring to physiological situations in which signaling molecules act in an immobilized state. Here, we studied platelet adhesion by thrombin, a key step in normal hemostasis and pathological arterial thrombosis. We generated a biofunctional nanosheet surface to mimic the in vivo solid-state interaction between platelets and thrombin at sites of injured tissues. We observed that <10 molecules readily activate platelets with high specificity, resulting in platelet adhesion and spreading. This number is much lower than expected from previous experiments in solution, in which the sole activation of platelets required a >1000-fold stoichiometric excess of thrombin. We conclude that immobilizing thrombin apposed to the membrane receptor allows platelets to respond with very high sensitivity. Moreover, we propose that irreversible cell activation may require several ligands to avoid activation by single, mislocalized signaling molecules. 相似文献
883.
Wei J Wang W Chopra I Li HF Dougherty CJ Adi J Adi N Wang H Webster KA 《The Journal of biological chemistry》2011,286(16):13995-14006
Brief periods of ischemia do not damage the heart and can actually protect against reperfusion injury caused by extended ischemia. It is not known what causes the transition from protection to irreversible damage as ischemia progresses. c-Jun N-terminal kinase-1 (JNK-1) is a stress-regulated kinase that is activated by reactive oxygen and thought to promote injury during severe acute myocardial infarction. Because some reports suggest that JNK-1 can also be protective, we hypothesized that the function of JNK-1 depends on the metabolic state of the heart at the time of reperfusion, a condition that changes progressively with duration of ischemia. Mice treated with JNK-1 inhibitors or transgenic mice wherein the JNK-1 gene was ablated were subjected to 5 or 20 min of ischemia followed by reperfusion. When JNK-1 was inactive, ischemia of only 5 min duration caused massive apoptosis, infarction, and negative remodeling that was equivalent to or greater than extended ischemia. Conversely, when ischemia was extended JNK-1 inactivation was protective. Mechanisms of the JNK-1 switch in function were investigated in vivo and in cultured cardiac myocytes. In vitro there was a comparable switch in the function of JNK-1 from protective when ATP levels were maintained during hypoxia to injurious when reoxygenation followed glucose and ATP depletion. Both apoptotic and necrotic death pathways were affected and responded reciprocally to JNK-1 inhibitors. JNK-1 differentially regulated Akt phosphorylation of the regulatory sites Ser-473 and Thr-450 and the catalytic Thr-308 site in vivo. The studies define a novel role for JNK-1 as a conditional survival kinase that protects the heart against brief but not protracted ischemia. 相似文献
884.
885.
Keck S Müller I Fejer G Savic I Tchaptchet S Nielsen PJ Galanos C Huber M Freudenberg MA 《Journal of immunology (Baltimore, Md. : 1950)》2011,186(9):5478-5488
In macrophages, two signaling pathways, dependent on MyD88 or TIR domain-containing adaptor-inducing IFN-β (TRIF) signaling, emanate from the LPS receptor TLR4/MD-2. In this study, we show that in murine bone marrow-derived mast cells (BMMCs), only the MyD88-dependent pathway is activated by LPS. The TRIF signaling branch leading both to NF-κB activation and enhanced proinflammatory cytokine production, as well as to IRF3 activation and subsequent IFN-β production, is absent in LPS-stimulated BMMCs. IRF3 activation is also absent in peritoneal mast cells from LPS-injected mice. We observed strongly diminished TRAM expression in BMMCs, but overexpression of TRAM only moderately enhanced IL-6 and did not boost IFN-β responses to LPS in these cells. A combination of very low levels of TRAM and TLR4/MD-2 with the known absence of membrane-bound CD14 are expected to contribute to the defective TRIF signaling in mast cells. We also show that, unlike in macrophages, in BMMCs the TRIF-dependent and -independent IFN-αβ responses to other recognized IFN inducers (dsRNA, adenovirus, and B-DNA) are absent. These results show how the response to the same microbial ligand using the same receptor can be regulated in different cell types of the innate immune system. 相似文献
886.
887.
Sanchez-Roman I Gomez A Gomez J Suarez H Sanchez C Naudi A Ayala V Portero-Otin M Lopez-Torres M Pamplona R Barja G 《Journal of bioenergetics and biomembranes》2011,43(6):699-708
Methionine dietary restriction (MetR), like dietary restriction (DR), increases rodent maximum longevity. However, the mechanism responsible for the retardation of aging with MetR is still not entirely known. As DR decreases oxidative damage and mitochondrial free radical production, it is plausible to hypothesize that a decrease in oxidative stress is the mechanism for longevity extension with MetR. In the present investigation male Wistar rats were subjected to isocaloric 40% MetR during 7 weeks. It was found that 40% MetR decreases heart mitochondrial ROS production at complex I during forward electron flow, lowers oxidative damage to mitochondrial DNA and proteins, and decreases the degree of methylation of genomic DNA. No significant changes occurred for mitochondrial oxygen consumption, the amounts of the four respiratory complexes (I to IV), and the mitochondrial protein apoptosis-inducing factor (AIF). These results indicate that methionine can be the dietary factor responsible for the decrease in mitochondrial ROS generation and oxidative stress, and likely for part of the increase in longevity, that takes place during DR. They also highlight some of the mechanisms involved in the generation of these beneficial effects. 相似文献
888.
889.
Anna Medyukhina Nadine Vogler Ines Latka Stefanie Kemper Markus Böhm Benjamin Dietzek Jürgen Popp 《Journal of biophotonics》2011,4(9):627-636
All‐optical microspectroscopic and tomographic tools have a great potential for the clinical investigation of human skin and skin diseases. However, automated optical tomography or even microscopy generate immense data sets. Therefore, in order to implement such diagnostic tools into the medical practice in both hospitals and private practice, there is a need for automated data handling and image analysis ideally implementing automized scores to judge the physiological state of a tissue section. In this contribution, the potential of an image processing algorithm for the automated classification of skin into normal or keloid based on second‐harmonic generation (SHG) microscopic images is demonstrated. Such SHG data is routinely recorded within a multimodal imaging approach. The classification of the tissue implemented in the algorithm employs the geometrical features of collagen patterns that differ depending on the constitution, i.e., physiological status of the skin. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
890.
Colombo F Baldan F Mazzucchelli S Martin-Padura I Marighetti P Cattaneo A Foglieni B Spreafico M Guerneri S Baccarin M Bertolini F Rossi G Mazzaferro V Cadamuro M Maggioni M Agnelli L Rebulla P Prati D Porretti L 《PloS one》2011,6(6):e21369