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  • 1
    Electronic Resource
    Electronic Resource
    ATLANTIK Genta, a New Concept of Gentamicin Loaded HAP/TCP Bone Substitute for Prophylactic Action-In Vitro Releasing Mechanisms Study (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 361-363 (Nov. 2007), p. 1203-1206 
    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: Despite systemic prophylaxis, infection rates after orthopedic surgery can reach morethan 1%. A new HAP/TCP bone substitute loaded with 125 mg of gentamicin was designed forprophylactic use. Its aim was to enhance the efficacy of systemic prophylactic treatments byincreasing the local antibiotic concentration. For prophylactic applications, release had to take placewithin 48 hours not to select antibiotic-resistant bacterial strains. The purpose of this study was toinvestigate the releasing mechanisms of gentamicin from the porous HAP/TCP matrix. The releaserate of gentamicin trough the porosities of the bone substitute was investigated in vitro, in 0.9%sodium chloride solution. The rate appeared to be related to the bone substitute volume and fitclassical diffusion laws. All the gentamicin was released in less than 48 hours: this rate correspondsto the recommendations for the prophylactic use of antibiotics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/56/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.361-363.1203.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Localization of endogenous osteocalcin in neonatal rat bone and its absence in articular cartilage: Effect of warfarin treatment (1990)
    Springer
    Virchows Archiv 417 (1990), S. 505-512 
    Details
    ISSN: 1432-2307
    Keywords: Osteocalcin ; Osteoblast ; Osteocyte ; Ultrathin frozen sections ; Warfarin treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunocytochemistry after cryoultramicrotomy was used to localize endogenous osteocalcin in bone (calvaria, femoral diaphysis) and epiphyseal femoral cartilage from 8-day-old rats treated (or mot) for 7 days with warfarin. Ultrathin frozen sections were incubated with goat antiserum against rat osteocalcin at high dilutions (2×10−4 to 2×10−6). In calvaria and femur of untreated rats, endogenous osteocalcin was observed in osteoblasts (cytoplasm and nucleus) and in the collagenous matrix. Osteocalcin appeared progressively in osteoblasts and bone matrix in the mineralization front, then increased in the regions of extended calcification. Osteocalcin was also detected in osteocytes but was not as abundant as in osteoblasts. In bone samples of warfarin-treated rats, endogenous osteocalcin was only detected in bone matrix but not in osteoblasts. Furthermore, osteocalcin was only observed if antiserum was not very dilute (2×10−2). In cartilage (hypertrophied and degenerative zones), osteocalcin was not observed in matrix and chondrocytes. However, it was found in the vicinity of matrix vesicles at the initial loci of calcification. Osteocalcin was never detected in the cartilage of warfarin-treated rats. Our results provide ultrastructural immunocytological evidence for the localization of endogenous osteocalcin in osteoblasts, the presence of osteocalcin in bone matrix and a direct gradient between the presence of osteocalcin and the calcification process. Osteocalcin is absent from cartilage, except possibly close to calcifying matrix vesicles. Warfarin inhibits the formation of osteocalcin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01625731
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  • 3
    Electronic Resource
    Electronic Resource
    Value of the bone biopsy in the diagnosis of industrial fluorosis (1978)
    Springer
    Virchows Archiv 380 (1978), S. 283-297 
    Details
    ISSN: 1432-2307
    Keywords: Bone biopsy ; Skeletal fluorosis ; Occupational medicine ; Morphometry ; Microradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Iliac crest biopsies taken from 43 men with industrial fluorosis were compared with control bone samples. The bone fluoride content was determined, histological examinations were made on stained sections and microradiographs, and morphometric analysis performed on the microradiographs alone. In the subjects with fluorosis, the bone fluoride content (5617±2143 ppm) was found to be significantly higher (P〈0.00005) than in control subjects (1036±627 ppm). It decreased slowly, however, after exposure had ceased (to about 50% in 20 years). The histological changes consisted of a nonspecific remodeling activity (resulting in increased trabecular bone volume and cortical porosity, as well as hypervascularization and linear formation defects) and modifications of the perilacunar walls (i.e., presence of mottled lacunae and enlarged lacunae). These histological changes were found more likely to occur when the bone fluoride content was high but no correlation between the two parameters was observed. Although certain clinical and radiological data associated with a high urine fluoride content can sometimes establish a diagnosis of skeletal fluorosis, many cases require the use of bone biopsy, which also provides a direct evaluation of the bone fluoride content and can establish the absence of any other bone disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431313
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  • 4
    Electronic Resource
    Electronic Resource
    Calcergy and calciphylaxis: Timed appearance of γ-carboxyglutamic acid and osteocalcin in mineral deposits (1983)
    Springer
    Calcified tissue international 35 (1983), S. 555-561 
    Details
    ISSN: 1432-0827
    Keywords: Calcergy ; Calciphylaxis ; Osteocalcin ; γ-Carboxyglutamic acid ; Vitamin K
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary γ-Carboxyglutamate (Gla), a calcium binding amino acid whose synthesis depends on vitamin K, has been found in association with pathologic calcifications. It is of interest therefore to examine the role of Gla-containing proteins in the formation of nonskeletal mineralized tissues. Calcergy and calciphylaxis, experimentally induced models of pathologic calcification, offer the opportunity to study the formation of mineral deposits in the absence of an endochondral sequence of bone formation. Before induction of subcutaneous calcinosis by topical treatment with the direct calcergen, KMnO4, or by challenging dihydrotachysterol-sensitized animals with FeCl2, control specimens contain no γ-carboxyglutamic acid. With the initial formation of cytoplasmic vesicles, calcium content of the tissues increases and Gla is detected. Gla levels are further elevated with the appearance of poorly crystalline apatite-like crystallites. Origin of protein bound Gla was established by positive identification of osteocalcin by radioimmunoassay. Gla and osteocalcin appear concomitant with the earliest mineral deposits observed by electron microscopy and micro X-ray analysis. The formation of organized extracellular mineral deposits allowed sufficient mineral accumulation for detection of an apatite-like pattern by X-ray diffraction with calcium, Gla, and osteocalcin increasing proportionately as mineral is deposited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405093
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  • 5
    Electronic Resource
    Electronic Resource
    A mathematical model for fluoride uptake by the skeleton (1993)
    Springer
    Calcified tissue international 52 (1993), S. 130-138 
    Details
    ISSN: 1432-0827
    Keywords: Fluoride ; Bone ; Osteoporosis ; Bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A mathematical model was developed that prediets fluoride accumulation and clearance from the skeleton based upon fluoride bioavailability, bone remodeling rate, and the fluoride binding characteristics of bone. It was assumed that fluoride binds to bone in a nonlinear fashion such that a smaller percentage of fluoride is bound to bone if fluoride intake is increased to high levels. Bone resorption rate was assumed to be proportional to the solubility of hydroxyfluorapatite which is inversely related to bone fluoride content. The predictions made by the model compared favorably with experimental results from fluoride uptake and clearance studies. Parametric studies done using the model showed the following: (1) fluoride can be cleared from the skeleton by bone remodeling, but fluoride clearance takes over four times longer than does fluoride uptake; and (2) fluoride uptake by the skeleton was positively associated with bone remodeling rate. However, the concentration of fluoride in newly formed bone does not decrease with reduced remodeling rates and surpasses 10,000 ppm for intakes of fluoride greater than 9 mg/day. For osteoporosis, daily dose and duration of fluoride treatment should be selected to avoid reaching a toxic cumulative bone fluoride content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308322
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