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排序方式: 共有281条查询结果,搜索用时 15 毫秒
71.
72.
Vi Khanh Truong Stuart Rundell Rimma Lapovok Yuri Estrin James Y. Wang Christopher C. Berndt David G. Barnes Christopher J. Fluke Russell J. Crawford Elena P. Ivanova 《Applied microbiology and biotechnology》2009,83(5):925-937
The influence of the ultrafine crystallinity of commercial purity grade 2 (as-received) titanium and titanium modified by
equal channel angular pressing (modified titanium) on bacterial attachment was studied. A topographic profile analysis of
the surface of the modified titanium revealed a complex morphology of the surface. Its prominent micro- and nano-scale features
were 100–200-nm-scale undulations with 10–15 μm spacing. The undulating surfaces were nano-smooth, with height variations
not exceeding 5–10 nm. These surface topography characteristics were distinctly different from those of the as-received samples,
where broad valleys (up to 40–60 μm) were detected, whose inner surfaces exhibited asperities approximately 100 nm in height
spaced at 1–2 μm. It was found that each of the three bacteria strains used in this study as adsorbates, viz. Staphylococcus aureus CIP 68.5, Pseudomonas aeruginosa ATCC 9025 and Escherichia coli K12, responded differently to the two types of titanium surfaces. Extreme grain refinement by ECAP resulted in substantially
increased numbers of cells attached to the surface compared to as-received titanium. This enhanced degree of attachment was
accompanied with an increased level of extracellular polymeric substances (EPS) production by the bacteria.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
73.
Renato Milani Carmen V. Ferreira José M. Granjeiro Edgar J. Paredes‐Gamero Rodrigo A. Silva Giselle Z. Justo Helena B. Nader Eduardo Galembeck Maikel P. Peppelenbosch Hiroshi Aoyama Willian F. Zambuzzi 《Journal of cellular biochemistry》2010,109(5):957-966
Cell adhesion on surfaces is a fundamental process in the emerging biomaterials field and developmental events as well. However, the mechanisms regulating this biological process in osteoblasts are not fully understood. Reversible phosphorylation catalyzed by kinases is probably the most important regulatory mechanism in eukaryotes. Therefore, the goal of this study is to assess osteoblast adhesion through a molecular prism under a peptide array technology, revealing essential signaling proteins governing adhesion‐related events. First, we showed that there are main morphological changes on osteoblast shape during adhesion up to 3 h. Second, besides classical proteins activated upon integrin activation, our results showed a novel network involving signaling proteins such as Rap1A, PKA, PKC, and GSK3β during osteoblast adhesion on polystyrene. Third, these proteins were grouped in different signaling cascades including focal adhesion establishment, cytoskeleton rearrangement, and cell‐cycle arrest. We have thus provided evidence that a global phosphorylation screening is able to yield a systems‐oriented look at osteoblast adhesion, providing new insights for understanding of bone formation and improvement of cell–substratum interactions. Altogether, these statements are necessary means for further intervention and development of new approaches for the progress of tissue engineering. J. Cell. Biochem. 109: 957–966, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
74.
<正> Natural surfaces with super hydrophobic properties often have micro or hierarchical structures.In this paper, the wettingbehaviours of a single droplet on biomimetic micro structured surfaces with different roughness parameters are investigated.Atheoretical model is proposed to study wetting transitions.The results of theoretical analysis are compared with those of experimentindicating that the proposed model can effectively predict the wetting transition.Furthermore, a numerical simulationbased on the meso scale Lattice Boltzmann Method (LBM) is performed to study dynamic contact angles, contact lines, andlocal velocity fields for the case that a droplet displays on the micro structured surface.A spherical water droplet with r_s= 15 μmfalls down to a biomimetic square-post patterned surface under the force of gravity with an initial velocity of 0.01 m·s~(-1) and aninitial vertical distance of 20 μm from droplet centre to the top of pots.In spite of a higher initial velocity, the droplet can stillstay in a Cassie state; moreover, it reaches an equilibrium state at t≈17.5 ms, when contact angle is 153.16° which is slightlylower than the prediction of Cassie-Baxter's equation which gives θ_(CB)=154.40°. 相似文献
75.
Experimental evaluation of current and novel approximations of articular surfaces of the ankle joint
Kinematics and flexibility properties of both natural and replaced ankle joints are affected by the geometry of the articulating surfaces. Recent studies proposed an original saddle-shaped, skewed, truncated cone with laterally oriented apex, as tibiotalar contact surfaces for ankle prosthesis. The goal of this study was to compare in vitro this novel design with traditional cylindrical or medially centered conic geometries in terms of their ability to replicate the natural ankle joint mechanics. Ten lower limb cadaver specimens underwent a validated process of custom design for the replacement of the natural ankle joint. The process included medical imaging, 3D modeling and printing of implantable sets of artificial articular surfaces based on these three geometries. Kinematics and flexibility of the overall ankle complex, along with the separate ankle and subtalar joints, were measured under cyclic loading. In the neutral and in maximum plantarflexion positions, the range of motion under torques in the three anatomical planes of the three custom artificial surfaces was not significantly different from that of the natural surfaces. In maximum dorsiflexion the difference was significant for all three artificial surfaces at the ankle complex, and only for the cylindrical and medially centered conic geometries at the tibiotalar joint. Natural joint flexibility was restored by the artificial surfaces nearly in all positions. The present study provides experimental support for designing articular surfaces matching the specific morphology of the ankle to be replace, and lays the foundations of the overall process for designing and manufacturing patient-specific total ankle replacements. 相似文献
76.
Sinner EK Reuning U Kök FN Saccà B Moroder L Knoll W Oesterhelt D 《Analytical biochemistry》2004,333(2):216-224
An optimized peptide-tethered artificial lipid membrane system has been developed. Integrins (cell adhesion receptors) were functionally incorporated into this membrane model and integrin-ligand interactions were analyzed by surface plasmon-enhanced fluorescence spectroscopy (SPFS). The transmembrane receptors alpha(v)beta(3) and alpha(1)beta(1) of the integrin superfamily were incorporated into a lipid-functionalized peptide layer by vesicle spreading. Consecutive layer formations were monitored by surface plasmon spectroscopy (SPS). Orientation and accessibility of the membrane receptor alpha(v)beta(3) was reliably assessed by specific and reproducible binding of selective antibodies. Moreover, full retention of the functional properties of this receptor was verified by specific and reversible binding of natural ligands. Functional integrity of incorporated integrins was maintained over a time period of 72 h. The integrin/extracellular matrix ligand complexes, whose formations are known to depend on the presence of divalent cations, were lost upon addition of ethylenediaminetetraacetate. Therefore, regeneration of the surface for further binding experiments with minimized unspecific ligand association was possible. These results demonstrate that integrins can be functionally incorporated into peptide-tethered artificial membranes. In combination with the SPS/SPFS method, this artificial membrane system provides a reliable experimental platform for investigation of isolated membrane proteins under experimental conditions resembling those of their native environment. 相似文献
77.
78.
On the basis of field and culture investigations, five species of the genera Trentepohlia and Printzina were found to occur in urban habitats in western Ireland: Trentepohlia abietina (Flotow) Hansgirg, T. aurea (Linnaeus) Martius, T. iolithus (Linnaeus) Wallroth, T. cf. umbrina (Kützing) Bornet, and Printzina lagenifera (Hildebrandt) Thompson et Wujek. These species formed perennial populations on a variety of substrata. T. abietina occurred on bark of trees; T. cf. umbrina occurred on stone walls; and P. lagenifera grew on several substrata, mainly cement and asbestos sheeting. T. aurea and T. iolithus were found on old concrete and cement walls; in particular, the latter species formed characteristic, extensive, deep‐red patches on many buildings. In culture, best growth and reproduction of these species were observed at 10 and 15° C, 16:8 h light:dark. Both in culture and in the field, reproduction took place by release of biflagellate swarmers behaving as asexual spores, germinating to produce new plants without any evidence of sexual fusion; release of biflagellate swarmers in the field was generally observed in all seasons throughout a whole annual cycle. Confirmation of the occurrence of sexual reproduction in Trentepohlia was not obtained. 相似文献
79.
Vascular endothelial cells cultured in the presence of fibroblast growth factor (FGF) devide actively when seeded at low or clonal cell densities and upon reachin confluence adopt a morphologic appearance and differentiated properties similar to those of the vascular endothelium in vovi. In this review, we present some of our recent observations regarding the characteristics (both structural and functional) of these endothelial cells and the role of FGF in controlling their proliferation and normal differentation. At confluence the endothelial cells from a monolayer of closely apposed and nondividing cell that have a nonthrombogenic apical surface and can no longer internalize bound ligands such as low-density lipoprotein (LDL). The adoption of these properties is correlated and possibly causally related to changes in the cell surface such as the appearance of a 60,000 molecular weight protein (CSP-60); the disappearance of fibronectin from the apical cell surface and its concomitant accumulation in the basal lamina; and a restriction of the lateral mobility of various cell surface receptor sites. In contrast, endothelial cells that are maintained in the absence of FGF undergo within three passages alterations that are incompatible with their in vivo morphologic apperarance and physiologic beharior. They grow at confluence on top of each other and hence can no longer adopt both the structural (CSP-60, cell surface polarity) and functional (barrier function, nonthrombogenicity) attributes of differentiated endothelial cell. Since these characteristics can be reacquired in response to readdition of FGF, in addition to being a mitogen FGF may also be involved in controlling the differentitation and phenotypic expression of the vascular endothelium. 相似文献
80.
Immobilized N-alkylated polyethylenimine avidly kills bacteria by rupturing cell membranes with no resistance developed 总被引:1,自引:0,他引:1
Several critical mechanistic and phenomenological aspects of the microbicidal surface coatings based on immobilized hydrophobic polycations, previously developed by us, are addressed. Using Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria, remarkable bactericidal action (up to a 10(9)-fold reduction in live bacteria count in the surface-exposed solution and a 100% inactivation of the surface-adhered bacteria) of an amino-glass slide covalently derivatized with N-hexyl,methyl-polyethylenimine (PEI) is found to be due to rupturing bacterial cell membranes by the polymeric chains. The bacteria fail to develop noticeable resistance to this lethal action over the course of many successive generations. Finally, the immobilized N-alkyl-PEI, while deadly to bacteria, is determined to be harmless to mammalian (monkey kidney) cells. 相似文献