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The phase transition of bilayers of 1,2-dibehenoyl-sn-glycero-3-phosphocholine (DBPC) induced by ice (H2O and D2O) melting has been investigated by infrared and Raman spectroscopy. Spectral changes observed at this transition are smaller at lower water content. These spectral changes are interpreted in terms of increased molecular mobility. Slightly different temperature dependencies are observed for various spectral parameters between samples dispersed in H2O and D2O. 相似文献
464.
Pagels Fernando Amaro Helena M. Tavares Tânia G. Casal Susana Malcata F. Xavier Sousa-Pinto Isabel Guedes A. Catarina 《Journal of applied phycology》2021,33(3):1379-1388
Journal of Applied Phycology - Microalgae have shown a great potential as a source of bioactive compounds, such lipidic compounds as fatty acids and carotenoids, with recognized benefit for human... 相似文献
465.
We propose a new cadherin family classification comprising epithelial cadherins (cadherin 17 [CDH17], cadherin 16, VE-cadherin, cadherin 6 and cadherin 20) containing RGD motifs within their sequences. Expression of some RGD cadherins is associated with aggressive forms of cancer during the late stages of metastasis, and CDH17 and VE-cadherin have emerged as critical actors in cancer metastasis. After binding to α2β1 integrin, these cadherins promote integrin β1 activation, and thereby cell adhesion, invasion and proliferation, in liver and lung metastasis. Activation of α2β1 integrin provokes an affinity increase for type IV collagen, a major component of the basement membrane and a critical partner for cell anchoring in liver and other metastatic organs. Activation of α2β1 integrin by RGD motifs breaks an old paradigm of integrin classification and supports an important role of this integrin in cancer metastasis. Recently, synthetic peptides containing the RGD motif of CDH17 elicited highly specific and selective antibodies that block the ability of CDH17 RGD to activate α2β1 integrin. These monoclonal antibodies inhibit metastatic colonization in orthotopic mouse models of liver and lung metastasis for colorectal cancer and melanoma, respectively. Hopefully, blocking the cadherin RGD ligand capacity will give us control over the integrin activity in solid tumors metastasis, paving the way for development of new agents of cancer treatment. 相似文献
466.
Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component. 相似文献
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Dorso-marginal epithelium, a distinct crescent-shaped region in the early gastrula of Bufo arenarum, appears after involution as a narrow dorso-median strip of archenteric endoderm close to the notochord. In explant cultures,
this layer showed an extreme dorsalizing activity, promoting the formation of notochordal structures from ventro-mesodermal
cells. In the presence of ectoderm, this inductive activity was expanded resulting in a wide range of dorso-lateral components
such as notochord, muscle, nephric tubules, mesothelium and mesenchyme. The mesodermal origin of these derivatives was confirmed
by the use of FDA (fluorescein-dextran-amine)-labelled explants. Extensive mesodermal development in cultures seems to require
cell contacts between the inner aspect of the dorso-marginal epithelium and mesodermal cells. When such contacts were prevented,
cultures would only differentiate erythrocytes as a result of a purely ectodermal stimulus. Bisection of the dorso-marginal
epithelium in whole embryos resulted in the development of a duplicated set of axial structures, clearly showing the role
of the epithelium as a dorsal organizer.
Received: 30 July 1996 / Accepted: 20 February 1997 相似文献