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  • 1
    Electronic Resource
    Electronic Resource
    New Method for Evaluating Material Blood Compatibility Using Microchannel Array (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 288-289 (June 2005), p. 495-498 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Microchannel array chips modified by metal deposition or polymer coating werecontacted with blood. Titanium (Ti), chromium (Cr) and gold (Au) films were deposited onto the microchannel array chips. Albumin (Alb) and MPC polymer (MPC) were coated onto other chips. Non-treated Si chips were used as a control. Whole blood was collected with 1000 units/ml heparin solution from young healthy volunteers. The passing time of a 100 µl portion of human whole bloodthrough these channels was measured under a pressure difference of 20 cm H2O. Simultaneously, the flow behavior of blood cells in channel was observed by an optical microscope and recorded by a video recorder. Platelet adhesion was observed on Si, Ti, Cr, and especially on Au. The blood pass-through time (BPT) increased in order of Ti, Si, Cr and Au. On the Alb- and MPC-coated chips, platelets were seldom observed and the BPTs were short in comparison with the metal chips. From these consequences, platelet adhesion depended on the materials. The BPT correlated well to the number of adherent platelets on the materials. Therefore, the blood coagulation reaction originated in platelet activation could be detected using microchannel array. We concluded that this method could be applied to evaluate initial blood compatibility of materials within several minutes in vitro
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/49/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.288-289.495.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Localization and orientation of the VirD4 protein of Agrobacterium tumefaciens in the cell membrane (1991)
    Springer
    Molecular genetics and genomics 228 (1991), S. 24-32 
    Details
    ISSN: 1617-4623
    Keywords: Crown gall tumour ; Agrobacterium tumefaciens ; Ti plasmids ; VirD4 protein ; Alkaline phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The virD4 gene of Agrobacterium tumefaciens is essential for the formation of crown galls. Analysis of the nucleotide sequence of virD4 has suggested that the N-terminal region of the encoded protein acts as a signal peptide for the transport of the VirD4 protein to the cell membrane of Agrobacterium. We have examined the localization and orientation of this protein in the cell membrane. When the nucleotides encoding the first 30 to 41 amino acids from the N-terminus of the VirD4 protein were fused to the gene for alkaline phosphatase from which the signal sequence had been removed, alkaline phosphatase activity was detectable under appropriate conditions. Immunoblotting with VirD4-specific antiserum indicated that the VirD4 protein could be recovered exclusively from the membrane fraction of Agrobacterium cells. Moreover, when the membrane fraction was separated into inner and outer membrane fractions by sucrose density-gradient centrifugation, VirD4 protein was detected in the inner-membrane fraction and in fractions that sedimented between the inner and outer membrane fractions. By contrast, the VirD4′/′alkaline phosphatase fusion protein with the N-terminal sequence from VirD4 was detected only in the inner membrane fraction. Treatment of spheroplasts of Agrobacterium cells with proteinase K resulted in digestion of the VirD4 protein. These results indicate that the VirD4 protein is transported to the bacterial membrane and anchored on the inner membrane by its N-terminal region. In addition, the C-terminal portion of the VirD4 protein probably protrudes into the periplasmic space, perhaps in association with some unidentified cellular factor(s).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00282443
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  • 3
    Electronic Resource
    Electronic Resource
    Plant-inducible recombination between the 25 bp border sequences of T-DNA in Agrobacterium tumefaciens (1986)
    Springer
    Molecular genetics and genomics 204 (1986), S. 374-382 
    Details
    ISSN: 1617-4623
    Keywords: T-DNA circularization ; Plant factor ; vir region ; 25 bp repeats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We developed a model system for detecting and assaying the circular forms of T-DNA which may be generated in Agrobacterium by intramolecular recombination between the 25 bp border repeats of T-DNA. We demonstrated using this system that the DNA region flanked by the 25 bp direct repeats is in fact circularized by recombination between these repeats in cells of Agrobacterium cocultured with tobacco protoplasts. Furthermore, quantitative analysis of the recombination revealed the following: (1) the recombination is also induced when the agrobacterial cells are incubated in protoplast-free conditioned medium prepared by filtering the protoplast culture. The conditioned medium is effective, even after it has been heated at 100°C. (2) The DNA region encompassing the virulence region of the Ti-plasmid is required for recombination. (3) The recombination takes place only between 25 bp repeats with the same orientation. On the basis of these results, we conclude that the circular form of T-DNA is generated by homologous recombination between the border repeats which is mediated by gene product(s) encoded by the virulence region of the Ti-plasmid. Either the recombination itself, or the expression of the virulence gene(s) responsible for the recombination, is induced by diffusible and heatstable factor(s) secreted by plant cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331013
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  • 4
    Electronic Resource
    Electronic Resource
    The promoter proximal region in the virD locus of Agrobacterium tumefaciens is necessary for the plant-inducible circularization of T-DNA (1987)
    Springer
    Molecular genetics and genomics 206 (1987), S. 174-177 
    Details
    ISSN: 1617-4623
    Keywords: Agrobacteium ; Ti plasmid ; T-DNA circularization ; virD genes ; Plant-inducible vir gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The formation of crown gall tumours involves the transfer of the T-DNA region of the Ti plasmid from Agrobacterium to plant cells and its subsequent integration into plant chromosomes. When agrobacteria are incubated with plant protoplasts or exudates of plants, the T-DNA region is circularized by recombination or cleavage and rejoining between the 25 bp terminal repeats; the formation of circular T-DNAs is thought to be one step in T-DNA transfer (Koukolikova-Nicola et al. 1985; Machida et al. 1986). We previously showed that the virulence region of the Ti plasmid is required for T-DNA circularization. In the present paper, we examined the circularization event in agrobacteria harbouring octopine Ti plasmids with mutations in various loci of the virulence region. The results clearly demonstrate that the gene(s) encoded in the virD locus are necessary for T-DNA circularization. In particular, the gene(s) present in the region proximal to the virD promoter are essential. We propose that roduct(s) of this gene have recombinase or endonuclease activity which specifically recognizes the 25 bp terminal repeats of T-DNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326554
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