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  • 1
    ISSN: 1432-0827
    Keywords: Osteogenesis ; Osteoinduction ; Bone ; Matrix ; Cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Bone matrix demineralized in 0.6 N HCl at 2° for 24 h and implanted in muscle in allogeneic rats possesses consistently reproducible bone morphogenetic activity. Experiments on implants of matrix, obtained from donors injected with3H-tyrosine or3H-tryptophan, or Na35SO4, suggest that bone morphogenetic property is a protein or apart of a protein that is (1) insoluble in buffer solutions, pH 3.6 and 5.0; (2) degraded in buffer solutions at pH 7.4 by an endogenous sulfhydryl-group neutral proteinase; (3) digested by trypsin at 15° within 8 h without solubilization of the helical regions, possibly even without degradation of the nonhelical ends of the bone collagen molecule, and without any loss of the periodic ultrastructure of the collagen fibrils; (4) degraded or removed by 0.1 N NaOH at 2° within 24 h without solubilization of collagen; (5) biologically active even after nitration of tyrosyl groups with tetranitromethane. The release of only one-third of the radioactivity with loss of nearly all yield of new bone by limited tryptic digestion of3H-borohydride-reduced matrix indicates that the bone morphogenetic response is the function of a non-collagenous component. Autoradiographs of implants of matrix with non-collagenous proteins labelled with3H-tryptophan,3H-tyrosine, or both3H-tyrosine and3H-phenyl-alanine demonstrate random dissemination of the radioactive constituents and no evidence of local transfer of labelled proteins or soluble protein derivatives. Hypothetically, the bone morphogenetic response is controlled by an insoluble acidic bone morphogenetic protein or polypeptide (BMP) and a soluble neutral proteinase (BMP-ase) resembling trypsin in activity except functionally more specific for BMP. Firmly bound but separable from bone collagen, BMP is one of many short-lived morphogenetic substances appearing and disappearing throughout embryonic development and persisting in postfetal life. Where the BMP receptor resides and how it activates cell mechanisms of differential repression and derepression of such genes as code for osteogenesis is unknown.
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  • 2
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Hydroxyapatite (HAP) has been used in orthopedics as an aid in bone grafts following surgery of bone tumors and osteoarthrosis, often promoting osteoconduction. The incorporation of antibiotics into HAP beads to prevent local infection would seem to be therapeutically effective. This report describes in vitro and in vivo release rate of cefotiam hydrochloride (CTM, 3.5 mg/bead) loaded into HAP beads (8.48 mm in diameter). Egg phosphatidylcholine (EPC) was also incorporated into HAP to control the rate of release of CTM. In vitro, 100% of CTM was released within 3 h from the EPC-free HAP beads. The rate of diffusion of CTM from HAP was prlonged with the incorporation of EPC. In vivo, 100% of CTM of the EPC-free CTM was released within 7 h but the rate of release of CTM from the EPC-CTM was extended. In vivo, the serum level of CTM reflected the rate of release of the antibiotics from the HAP bead. We conclude that EPC is useful in controlling the diffusion rate of CTM from HAP. © 1992 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 3
    ISSN: 0730-2312
    Keywords: procollagen synthesis ; human osteosarcoma cells ; 1,25-dihydroxyvitamin D3 ; type I collagen ; proline hydroxylation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The kinetics of type I procollagen synthesis in a human osteosarcoma cell line, MG 63, were investigated after treatment with 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3), a hormonal inducer of phenotypic differentiation. Pulse label and chase experiments demonstrated greatly enhanced production and more rapid reduction of intracellular procollagen molecules in the 1,25-(OH)2 D3-treated cells as compared to the nontreated case. After a chase for 1 h, labeled procollagen was reduced by nine-tenths in 1,25-(OH)2 D3-treated cells, while half of the radioactivity still remained in nontreated cells. The expression rate of type I collagen, which was examined by pulse label experiment, was elevated in association with an increase in the mRNA coding for the type I collagen α1 chain by 1,25-(OH)2 D3 treatment. However, the amount of intracellular procollagen present after 4 h continuous labeling was almost the same, independent of the 1,25-(OH)2 D3 treatment. Thus, we conclude that strage of the molecule was not affected. The results therefore suggest an increase in both the synthesis and secretion of type I collagen. The 1,25-(OH)2 D3 treatment was also found to induce the α subunit of prolyl 4-hydroxylase and to be associated with an elevated level of hydroxyproline in the procollagen. Moreover, gelatinase B-resistant procollagen molecules, indicative of intracellular procollagen molecules in the stable triple helical form, were detected only in the 1,25-(OH)2 D3-treated cells. These data suggest more efficient proline hydroxylation is involved in rapid secretion of procollagen after hormone administration. The present evidence points to posttranslational control of procollagen synthesis. J. Cell. Biochem. 65:542-549. © 1997 Wiley-Liss Inc.
    Additional Material: 5 Ill.
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  • 4
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Various forms of hydroxyapatite (HAP) materials have been developed for use as bone grafts. Since the risk of local infection is associated with surgery, it seems reasonable to incorporate drugs such as antibiotics into implant materials. We therefore investigated the characteristics of drug incorporation into a spherical porous HAP bead (diameter = 8.48 mm, bulk porosity = 0.439) and its in vitro release behavior. Cefotiam (CTM) was used as a model antibiotic. Because of nonuniform pore distribution in the bead, distribution of CTM was estimated from the amounts of CTM experimentally determined at three different sites: the surface, halfway to the center, and the center of the beads. The results indicated that 90% of the drug was incorporated in the concentric outer 0.387 (radius = 1) section of the bead. CTM was released with a short lag time when the dry HAP bead was placed in water. Incorporation of CTM with egg phosphatidylcholine eliminated initial lag time and decreased the release rate of the drug from the bead. The lipid load was useful in controlling the release of CTM from the beads. In addition, to protect relatively unstable drugs from humidity and avoid contamination of drug-incorporated HAP beads an apparatus was designed with which the beads could be enclosed in vials in vacuo and under aseptic conditions on a bench-scale basis.
    Additional Material: 7 Ill.
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  • 5
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study was conducted to investigate whether hydroxyapatite (HAP) is appropriate as a percutaneous drug carrier for estradiol (E2) for the suppression of bone loss. Ten-week-old female Sprague-Dawley rats were subjected either to bilateral ovariectomy (OVX) or to sham surgery (control). Ovariectomized rats were implanted percutaneously with E2-HAP disks containing low, medium or high doses of estradiol (50, 250, or 500 μg E2/rat, respectively). Ovariectomized rats without implant and OVX rats implanted only with HAP served as additional controls. All rats were sacrificed 90 days after surgery. At the end of the experiment, bone mineral density of the lumbar spine was measured by dual energy X-ray absorption, and serum E2 was assayed by radioimmunoassay. The bone mineral density of OVX and HAP-treated OVX rats decreased by 18% compared to sham surgery rats, but decreased by only 13, 7, and 3% in rats treated with 50, 250, and 500 μg E2/rat, respectively. The in vitro release of E2 from E2-HAP devices was determined by an HPLC method. Estradiol release from the HAP devices followed almost a zero-order kinetics. Estradiol remained intact in E2-HAP implants for up to six months when stored at 5, 25, and 40°C. This study indicates that E2-HAP implants are effective in suppressing bone loss in the spine of OVX rats in a dose-dependent manner. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 6
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase (TIMPs) play an important role in tissue destruction and remodeling. Nine samples of cement interface tissues from nine patients who had failed cemented total hip arthroplasty (THA) were obtained for revision of THA and analyzed on mRNA expression of MMPs and TIMPs. The preoperative serial radiographic examinations revealed an apparent clear zone around all implants. We excluded septic loosening as one of the factors affecting THA. Three samples were obtained from three different sites of the acetabular interface tissue in each patient. After extraction of total RNA from 27 samples, we used the reverse-transcriptional polymerase chain reaction (RT-PCR). mRNA of MMP-1, -2, -3, -9, and TIMP-1 and -2 was detected in the interface tissue. MMP-10 mRNA was not detected, yet MMP-1 and MMP-3 mRNA were commonly observed. TIMP-2 mRNA was also strongly expressed compared to TIMP-1. It was thus demonstrated that MMPs and TIMPs were produced locally in the cemented tissue of THA loosening. These findings may suggest that MMPs and TIMPs expressed around the implants play a critical role in the progression of aseptic loosening of THA. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 7
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The bone-cement interface tissue of failed total hip arthroplasty (THA) has inflammatory characteristics, such as the presence of prostaglandin E2 and interleukin 1 (IL-1). We considered that the bone-cement interface tissue could be the site of granulomatous inflammation caused by a foreign-body reaction. It has been demonstrated that inflammatory cytokines and chemokines have an important role in granulomatous inflammation. Bone-cement interface tissue was obtained at revision from nine patients with failed cemented THA, and the role of macrophages was assessed by immunohistochemistry, electron microscopy, and molecular biological techniques. We used the reverse-transcriptional polymerase chain reaction to examine the expression of mRNA for IL-1α, IL-1β, tumor necrosis factor α (TNFα), macrophage inflammatory protein (MIP)-1α, MIP-1β, IL-8, and monocyte chemoattractant protein. Polyethylene debris surrounded by macrophages and phagocytosis of debris by macrophages was frequently observed in the interface tissue. Macrophage activation and the production of inflammatory cytokines such as 1L-1 and TNFα might induce the development of interface tissue. Expression of chemokine mRNAs was also commonly seen, suggesting that this led to recruitment of macrophages into the bone-cement interface tissue. Debris released from implants appears to cause activation of macrophages and the production of inflammatory cytokines and chemokines that induce cellular recruitment into interface tissue. This mechanism might form a vicious cycle that aggravates THA loosening. © 1997 John Wiley & Sons, Inc.
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