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  • 2000-2004  (3)
  • 1990-1994  (17)
  • 1965-1969  (1)
Materialart
Erscheinungszeitraum
Jahr
  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 677-683 
    ISSN: 1432-0614
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract A protein modification method has been developed for the production of human big endothelin (ET)-1. Production of a large quantity of big ET-1 by the method described here is expected to facilitate future experiments such as X-ray crystallography and nuclear magnetic resonance studies, aimed at understanding the tertiary structure of big ET-1 and its dynamics. The plasmid pETB-50 used for the synthesis carries the gene for a fusion protein consisting of 34-amino acid (aa) residues of an N-terminal portion of β-galactosidase and the 38-aa residues of big ET-1. The fusion protein ETB-50P contains an arginine residue in the big ET-1 portion at its second C-terminal site and three lysine residues including the C-terminal site in the β-galactosidase portion, all of which are susceptible to trypsin. Tryptic digestion of the fusion protein quantitatively produced big ET-1 (1–37), which is depleted in the C-terminal serine. However, a treatment of the fusion protein with 1,2-cyclohexanedione prior to tryptic digestion gave full-length big ET-1 with N7,-N8-(1,2-dihydroxycyclohex-1,2-ylene)-arginine. This modification was reversed to the intact arginine residue when the modified big ET-1 was incubated in 0.5 M TRIS-HCI buffer, pH 8.0. Consequently, a combination of such a reversible protein modification and tryptic digestion gave 1.74 mg of recombinant big ET-1 from 2.01 of culture broth. The procedure described here may be applied to produce other arginine-containing peptides from fusion proteins.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Computational mechanics 13 (1994), S. 391-399 
    ISSN: 1432-0924
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The lattice gas automata (LGA) is a microscopic model recently introduced to the field of fluid dynamics. The lattice Boltzmann equation (LBE) is an alternative implementing scheme of the LGA, which is totally free of noise. The modeled fluid is called as the cellular automaton (CA) fluid. It is known that the pressure of the CA fluid contains a velocity dependent part. It reflects the simple and discrete nature of the model and either brings about unphysical oscillation in the flow energy or spoils the pressure field of the simulated flow. In this paper, we begin with a general introduction of the lattice gas models. Then we give a full description for such spurious terms and suggest a compensation method to eliminate the effect in the lattice Boltzmann model. Four numerical simulations are used as illustration for the effectiveness of this method.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 13
    ISSN: 1432-1203
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. An inv(11)(q13.5;q25) inversion was previously identified in a 9-month-old male patient with complex cyanotic heart defects, altered lung lobation, symmetric liver, and abnormally lobulated spleen (polysplenia). This chromosomal rearrangement was inherited from the phenotypically normal father. We termed these regions DHTX-A (disrupted in heterotaxy) –A at 11q13.5 and DHTX-B at 11q25. Here, we report the isolation and characterization of the inversion breakpoints and the gene that is disrupted by the DHTX-A breakpoint. The putative DHTX is identical to the UVRAG gene, which was originally identified as a gene that complements the UV sensitivity of xeroderma pigmentosum complementation group C. The 4-kb mRNA was found to be encoded by a large gene, at least 300 kb long, composed of 15 exons. The function of the gene product remains largely unknown. However, the near central portion of the UVRAG protein is predicted to contain a coiled-coil domain, which has been implicated in mediating protein-protein interactions. Southern analyses and fluorescence in situ hybridization (FISH) revealed that the DHTX-A breakpoint in the patient and his father lies within the intron between exons 6 and 7 of UVRAG. Northern blot analysis indicated strong expression in human fetal and adult tissues and in mouse embryonic day-7 and adult tissues, respectively. Whole mount in situ hybridization also showed that the Uvrag gene is expressed in the presomite-stage embryo. Several hypotheses are discussed to explain the relationship between the chromosomal inversion and the accompanying phenotypes.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Experiments in fluids 8 (1990), S. 249-256 
    ISSN: 1432-1114
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract A test tunnel for the study of airfoil performances under air/water two-phase flow condition has been designed and constructed. This facility will serve for a better understanding of the flow phenomena and characteristics of hydraulic machinery under gas/ liquid two-phase flow operating conditions. At the test section of the tunnel, a two-dimensional isolated airfoil or a cascade of airfoils is installed in a two-phase inlet flow with a uniform velocity (up to 10 m/s) and void fraction (up to 12%) distribution. The details of the tunnel structure and the measuring systems are described and the basic characteristics of the constructed tunnel are also given. As an example of the test results, void fraction distribution around a test airfoil is shown.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Mineralium deposita 29 (1994), S. 249-256 
    ISSN: 1432-1866
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract A test tunnel for the study of airfoil performances under air/water two-phase flow condition has been designed and constructed. This facility will serve for a better understanding of the flow phenomena and characteristics of hydraulic machinery under gas/ liquid two-phase flow operating conditions. At the test section of the tunnel, a two-dimensional isolated airfoil or a cascade of airfoils is installed in a two-phase inlet flow with a uniform velocity (up to 10 m/s) and void fraction (up to 12%) distribution. The details of the tunnel structure and the measuring systems are described and the basic characteristics of the constructed tunnel are also given. As an example of the test results, void fraction distribution around a test airfoil is shown.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 16
    ISSN: 1432-2013
    Schlagwort(e): Calcium oscillations ; Muscarinic receptor ; Calcium stores ; G protein ; Heparin ; Ryanodine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In single cells isolated from guinea-pig ileal smooth muscle, held under voltage clamp at −40 mV or −50 mV by patch pipette in the whole-cell recording mode, carbachol (CCh) evoked an oscillatory inward cationic current. The frequency of current oscillations increased with increasing CCh concentration. CCh-evoked current oscillations were followed very closely by oscillations in intracellular free Ca2+ estimated from the Indo-1 signal, and were abolished by inclusion of EGTA in the pipette solution. Ryanodine and heparin, but not nifedipine, blocked the generation of current oscillations. CCh-evoked current oscillations were abolished upon withdrawal of extracellular calcium and restored upon its reintroduction. Inclusion of GTP[γS] in the pipette solution caused the generation of an oscillatory inward current, which was blocked by ryanodine. The present results are consistent with the hypothesis that CChevoked cationic current is gated by activation of a G protein and is steeply dependent on [Ca2+]i, fluctuations in the release of Ca2+ from stores during carbachol's action produce oscillations in [Ca2+]i which cause similar oscillations in the cationic current.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 17
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract Interposed fibrous tissue at bone–implant interfaces was quantitatively measured in the presence or absence of polyethylene (PE) or alumina particles. Three different conditions of the interface were designed by implanting a pre-polymerized polymethylmethacrylate (PMMA) plug (plug group), a doughy PMMA (injection group) and a hydroxyapatite (HA) plug (HA group) in the hole drilled at the intercondylar notch of rabbit knees. PE (170±18 μm) or alumina particles (88±26 μm) were repeatedly administered into the knee joints at one month intervals (six times). All animals were sacrificed seven months after the implantation. The bone–implant interface was histomorphometrically examined using undecalcified ground sections. In the plug group, the PE particles significantly increased the extent of the interposed fibrous tissue (p 〈 0.05), while the alumina particles showed no effect. In contrast, both particles showed no significant effects in the injection and the HA groups. These results indicate that both particle characteristics and conditions of the bone–implant interface affected particle-induced fibrous tissue interposition. The loose PMMA plug with PE particles induced the greatest amount of fibrous tissue interposition. ©2000 Kluwer Academic Publishers
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 5 (1994), S. 225-231 
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: For biocompatibility evaluation, orthopaedic and dental biomaterials are often implanted into bone after drilling. Bone repair in the drilled hole may be affected by bone damage attributed to drilling, thus influencing the bone response to biomaterials. The drilling parameters (the speed of rotation and irrigation) were investigated histologically. Three holes were drilled in each rabbit tibia with different conditions; three speeds (200, 500 and 5000 r.p.m.) and the use of central irrigation or not. Rabbits were killed immediately, 3 days, 2 weeks or 4 weeks post-operatively. India ink was injected in several rabbits just after drilling to investigate the extent of local ischaemia. The drilling quality was evaluated with regard to hole geometry, initial thermal damage and later bone healing process. For 500 or 200 r.p.m. the initial thermal damage, shown by the degree of ischaemia, was less than for 5000 r.p.m. drilling, but the hole edge was not always cleanly cut. This uneven cut edge was considered not to influence the bone-healing process. Drilling at 200 r.p.m. introduced a lower degree of circularity. The subsequent bone formation was retarded by 5000 r.p.m. drilling, presumably due to thermal damage and vascular obstructions. The irrigation was effective in reducing the ischaemic area. These results suggest that a speed of about 500 r.p.m. may be recommendable for intraosseous implantation of biomaterials. The central irrigation system is considered effective in reducing the ischaemic area.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 5 (1994), S. 237-241 
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: For biocompatibility testing, cylindrical specimens are often inserted into drilled cortical defects. However, little attention has been paid to the drilling conditions. Our previous experience revealed that bone formation in drilled cortial defects was delayed by 5000 r.p.m. drilling due to thermal necrosis around the hole compared with 500 r.p.m., and the use of irrigation was effective in reducing the degree of local ischaemia. Therefore, this experiment was performed to investigate the short- and long-term effects of the drilling conditions on bone response to cylindrical porous hydroxyapatite implants. Two holes were drilled in rabbit tibia diaphysis with two different drilling conditions: 500 r.p.m. with irrigation and 5000 r.p.m. without irrigation. Rabbits were killed at 2 or 12 weeks post-operatively. The bone formation on the hole edge, on the implant surface and within the implant pores was investigated. At 2 weeks post-operatively the area of newly formed bone within the implant pores at 500 r.p.m. was significantly greater, whereas there was no difference at 12 weeks. These results indicate that the drilling conditions affect the short-term bone response to the implants. Therefore, the drilling conditions must be taken into consideration when investigating the early bone response to materials implanted into drilled cortical defects.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 20
    ISSN: 1573-4838
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: To investigate the biological process of aseptic component loosening caused by polyethylene wear debris, nine rabbits were implanted with acrylic cement into the non-weight-bearing intercondylar notch of distal femur. Six animals were administrated the particles of polyethylene into the knee joint repeatedly for 12 weeks. At the bone-cement interface, thin connective tissue was observed, while bone sometimes existed directly next to the acrylic cement. The percentage of the length of interposed fibrous tissue against the total length of bone-cement interface was measured. The percentage was 15.8±10.3 in the polyethylene-injected group and 8.3±7.7 in the control group (no significance). While not significant, the amount was greater in the polyethylene-injected group. Thus it is proposed that the polyethylene particles played a role in bone resorption and fibrous tissue formation at the bone—cement interface. In some specimens, macrophages and foreign body giant cells that surrounded the particles near the articular surface were seen to cause resorption of bone. It is supposed that this phenomenon is similar to the focal osteolysis that is sometimes observed around a prosthetic component.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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