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  • Chromium  (1)
  • Prostheses, porous-coated  (1)
  • disaccharide units  (1)
  • 1
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 14 (1992), S. 277-287 
    ISSN: 0887-3585
    Schlagwort(e): α-helix ; lysine residues ; disaccharide units ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: A model of heparin bound to bovine platelet factor 4 (BPF4) was completed using a graphically designed heparin molecule and the crystallographic coordinates of the native bovine platelet factor 4 tetramer. The oligosaccharides had a chain length of at least eight disaccharide units with the major repeating disaccharide unit consisting of (I→4)-O-(α-L-idopyranosyluronic acid 2-sulfate)-(l→4)-(2-deoxy-2-sulfamino-2-D-glucopyra-nosyl 6-sulfate). Each disaccharide unit carried a -4.0 charge. The structure of BPF4 was solved to 2.6 Å resolution with R = 0.237. Each monomer of BPF4 contains an α-helix lying across 3 strands of antiparallel β-sheet. Each helix has four lysines, which have been implicated in heparin binding. These lysine residues are predominantly on one side of the helix and are solvent accessible. Electrostatic calculations performed on the BPF4 tetramer show a ring of strong, positive charge which runs perpendicularly across the helices. Included in this ring of density is His-38, which has been shown by NMR to have a large pKa shift when heparin binds to BPF4. Our model of heparin bound to PF4 has the anionic polysaccharide perpendicular to the α-helices, wrapped about the tetramer along the ring of positive charge, and salt linked to all four lysines on the helix of each monomer. © 1992 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 0736-0266
    Schlagwort(e): Cobalt ; Chromium ; Nickel ; Total knee arthroplasty ; Total hip arthroplasty ; Prostheses, porous-coated ; Life and Medical Sciences
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Co, Cr, and Ni concentrations were determined by electrothermal atomic absorption spectrophotometry in serum and urine specimens collected from a group of 28 patients at intervals of from 1 day to 2.5 years after total knee or hip arthroplasty with porous-coated prostheses fabricated of Co-Cr alloy (ASTM F-75-82). Two control groups were also tested: (a) 42 healthy adults and (b) 16 orthopaedic patients after total knee or hip arthroplasty with porous-coated prostheses fabricated predominantly of Ti-Al-V alloy (ASTM F-136-84). All prostheses contained polyethylene components to avoid metal-to-metal contact. Mean Co concentrations in serum and urine were slightly increased in patients with Co-Cr knee implants at 6-120 weeks after surgery, compared with (a) preoperative values, (b) corresponding values in patients with Co-Cr hip implants, and (c) corresponding values in control patients with Ti-Al-V knee and hip prostheses. Substantially increased Co levels were observed in serum and urine of two patients at 7 weeks and 22 months postarthroplasty, associated with loosening of the prostheses; one of the patients also had elevated Cr levels in serum and urine. Although ASTM F-75-82 and F-136-84 alloys contain very little Ni (〈1.0 and 〈0.2% Ni, respectively, by wt), mean Ni concentrations in serum and urine were greatly increased at 1-2 days after implantation of Ti-Al-V and Co-Cr prostheses, diminishing by 2 weeks. The postoperative hypernickelemia and nickeluresis may reflect contamination of the operative field with Ni-containing particles from the drills, cutting jigs, and drilling jigs, or it may represent a previously unrecognized pathophysiological response to surgery.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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