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  • 1
    Digitale Medien
    Digitale Medien
    ACTIVITY OF ANTI-INFLAMMATORY STEROIDS UPON FIBROBLASTS AND BONES (1970)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 82 (1970), S. 0 
    Details
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2133.1970.tb08007.x
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  • 2
    Digitale Medien
    Digitale Medien
    The progress of the periodontal syndrome in the rice rat (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 16 (1981), S. 0 
    Details
    ISSN: 1600-0765
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Several morphometric and cellular parameters were studied in the rice rat (Oryzomys palustris). When fed a soft, high carbohydrate diet, a severe periodontal disease occurred, with significant alterations in the morphometric and cellular endpoints observed. Weaned animals were placed on a high carbohydrate diet for periods of 6, 12 or 18 weeks. There was a linear, rapid loss of bone by 18 weeks, approaching a 75 % loss of original bone. Vascular spaces decreased as the remaining connective tissue became fibrotic in character. The percentage of the interdental test site which was destroyed by periodontal disease increased dramatically over the time of the experiment. The numbers of fibroblasts per mm of bone surface increased slightly at the 18 week period; osteoblasts were unchanged at any period. The numbers of osteoclast nuclei rose dramatically by 12 weeks, and these cell nuclei remained at increased levels at 18 weeks. Also, the numbers of inflammatory cells residing at the bone surface increased greatly by 18 weeks time. Finally, the numbers of 3H-TdR labeled periodontal ligament (PDL) fibroblasts increased significantly at both 12 and 18 weeks time. These cellular changes and their relation to the bone loss due to periodontal disease are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0765.1981.tb00976.x
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  • 3
    Digitale Medien
    Digitale Medien
    The progress of the periodontal syndrome in the rice rat (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 16 (1981), S. 0 
    Details
    ISSN: 1600-0765
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The effects of a diphosphonate, dichloromethylene diphosphonate (C12MDP) were studied using the rice rat as a model of periodontal bone loss. C12MDP was given in daily subcutaneous injections at dosages of 0 (control), 0.1, 1.0, or 10.0 mg/kg/day; these treatments were continued for periods of 6, 12, or 18 weeks. The amount of alveolar bone was increased over age matched controls at the 1.0 and 10.0 mg/kg/day doses at 6 weeks; at 12 and 18 weeks, all doses including 0.1 mg/kg/day showed increases in bone over controls. Due to increased connective tissue fibrosis, the CI2MDP treated animals had fewer vascular spaces. Also, the amount of destroyed tissue in the interdental test site was increased in animals given 10.0 mg/kg/day of C12MDP. The number of fibroblasts per mm of bone surface decreased slightly at 6 weeks, but was otherwise not different from controls in treated animals at 12 and 18 weeks. Numbers of osteoblasts decreased greatly at all doses at both 12 and 18 weeks time. There were no significant differences between treated and control animals in the number of osteoclast nuclei per mm bone surface. Also, the numbers of inflammatory cells residing at the bone surface increased at all time periods in the 10.0 mg/kg/day dose group. Finally, the proliferative activity of PDL fibroblasts decreased dramatically at all time periods in the 10.0 mg/kg/day dose group. The response of the proximal tibia to C12MDP was compared to the alveolar bone response in these animals by measuring amounts of bone in respective areas. While the dose response curves are similar, the tibiae showed greater increases in bone mass.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0765.1981.tb00995.x
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  • 4
    Digitale Medien
    Digitale Medien
    Hits to bone cell nuclei from nonuniform radioactive labels (1994)
    Springer
    Radiation and environmental biophysics 33 (1994), S. 189-200 
    Details
    ISSN: 1432-2099
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract The stochastic aspects of α-particle traversals through nuclei of bone-lining cells from nonuniform radioactive labels are worked out. Both the residence time of the target and the hit rate are considered random variables. It is shown that with any type of bone remodeling the fraction of cells not hit increases with increasing nonuniformity of the label concentration. Thus, a completely uniform concentration represents the most dangerous situation. A possible negative correlation between residence times and hit rates, observed in some experiments, tends to decrease the probability of α-particle hits. As a practical application, the theory is applied to the International Commission on Radiological Protection model of the distribution of239 Pu in the human body. In the case of 50 years of chronic ingestion of 1 annual limit of intake (ALI) per year for class W and chronic inhalation of 1 ALI/year for class Y compounds, more than 19.4 and 8.5% of the nuclei of bone-lining cells are traversed by at least one α-particle, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01212675
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  • 5
    Digitale Medien
    Digitale Medien
    Statistics of hits to bone cell nuclei (1993)
    Springer
    Radiation and environmental biophysics 32 (1993), S. 87-98 
    Details
    ISSN: 1432-2099
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract The statistics of hits to the nuclei of bone cells irradiated from alpha sources labeling bone tissue is described. It is shown that the law of remodeling of a bone structural unit (BSU), which describes the distribution of quiescence periods of this unit, affects the statistics of hits. It the irradiation of bone cells occurs during the whole cell cycle, the mean number of hits is independent of the law of remodeling. In this case the variance of hits has the minimum value for constant quiescence periods of BSUs (deterministic remodeling) and the maximum value for exponentially distributed quiescence periods (random remodeling). For the first generation of bone cells, i.e. for the cells which existed at the moment of the uptake of the nuclide, the mean number of hits depends on the law of remodeling. For random remodeling the mean number is equal to the mean value for the complete remodeling cycle. For deterministic remodeling the mean is only half this value. For the first generation of bone cells, changing the law of remodeling from random to deterministic increases the probability of no hits to the nuclei of bone cells. For the same mean value of hits, the difference does not exceed 13.3 % of the total number of cells. For the subsequent generations of bone cells, such a change of the law of remodeling decreases the probability of no hits by 20.4%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01212795
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  • 6
    Digitale Medien
    Digitale Medien
    Electrophysiological properties of osteoblastlike cells from the cortical endosteal surface of rabbit long bones (1984)
    Springer
    Calcified tissue international 36 (1984), S. 401-408 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Membrane potential ; Electrolyte and protein contents ; Cell pH ; Cyclic AMP and hormonal preparations ; Endosteal bone cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The mean transmembrane potential of cultured osteoblastlike cells isolated from the cortical endosteal surface of rabbit long bones was −16.9±0.64 mV (n=335). Elevation of potassium concentration in medium caused a decrease in potential. As the external concentration of potassium reached 15 mmol/liter and above, there was a linear relationship between the potassium concentration in log scale and the membrane potential with a slope of −13 mV per 10-fold change in external potassium concentration. Dibutyryladenosine 3′,5′-cyclic monophosphate, parathyroid extract, hydrocortisone, and sodium fluoride all depolarized the membrane of osteoblast-like cells after both short (1–2 h) and long (24 h) exposures at suitable doses, whereas calcitonin and prostaglandin E2 hyperpolarized the membrane after long exposures. The Na+, K+ and Cl− concentrations of cultured osteoblastlike cells were 0.538, 0.984, and 0.358 mmol/g protein or 52.6, 96.3, and 35.0 mmol/liter cell water, respectively. The protein content of these cells was 8.18±0.6 g/100 g cells and the water content was 83.7 g/100 g cells. The above-mentioned chemical and hormonal preparations in doses that produced significant changes in the membrane potential of these cultured cells did not alter their electrolyte or protein contents 24 h after exposure. Intracellular pH of cultured osteoblastlike cells as determined by [14C]-dimethyloxazolidine-2,4-dione and3H2O averaged 7.03 ± 0.11 when the pH of culture medium was maintained at 7.4. Calculations based on the values for the membrane potential and the electrolyte concentrations observed in this study indicate that Na+, and H+, and Cl− are actively transported out of the cells and K+ into the cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02405352
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  • 7
    Digitale Medien
    Digitale Medien
    Production of new trabecular bone in osteopenic ovariectomized rats by prostaglandin E2 (1992)
    Springer
    Calcified tissue international 50 (1992), S. 80-87 
    Details
    ISSN: 1432-0827
    Schlagwort(e): PGE2 ; Ovariectomy ; Rats ; New bone trabeculae ; Positive balance ; Accelerated bone turnover
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Serum chemistry and bone morphometry of the proximal tibial metaphysis were performed in 3-month-old double fluorescent-labeled, female Sprague-Dawley rats subjected to bilateral ovariectomy or sham surgery for 4 months prior to treatment with 0, 0.3, 1, 3, or 6 mg of prostaglandin E2 (PGE2)/kg/day subcutaneously for 30 days. The 4-month postovariectomized rats possessed an osteopenic proximal tibial metaphysis with 7% trabecular area compared with controls (19%). PGE2 treatment elevated osteocalcin levels and augmented proximal tibial metaphyseal bone area in ovariectomized and sham-operated rats. Osteopenic, ovariectomized rats treated with 6 mg PGE2/kg/day for 30 days restored bone area to levels of agematched sham-operated rats. Morphometric analyses showed increased woven and lamellar bone area, fluorescent-labeled perimeter (osteoblastic recruitment), mineral apposition rate (osteoblastic activity), bone formation rate (BFR/BV), and longitudinal bone growth. These dramatic bone changes were all significantly increased at the doseresponse manner. This study showed that in vivo PGE2 is a powerful activator of bone remodeling, it increases both bone resorption and bone formation, and produces an anabolic effect by shifting bone balance to the positive direction. Furthermore, PGE2-induced augmentation of metaphyseal bone area in ovariectomized rats was at least two times greater than in sham-operated rats.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00297302
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  • 8
    Digitale Medien
    Digitale Medien
    Trabecular bone structural variation in biopsy sites of the beagle ilium (1982)
    Springer
    Calcified tissue international 34 (1982), S. 391-395 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Ilium ; Trabecular bone ; Biopsy ; Variability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Iliac trabecular bone sites were studied in 2 male and 2 female adult beagles to determine normal structural variability among different sites, and to identify transilial biopsy sites with minimum structural variation. Only sites that provided adequate amounts of trabecular bone were studied. Trabecular bone area and perimeter were measured on microradiographs of ground sagittal sections using a Quantimet 720 image analyzer, and percent bone, perimeter to area ratio, and mean trabecular width were calculated. Over 100% variation was found in the parameters studied among sections from different sites within the same animal. However, variability was minimal among sections obtained more than 2 mm from the lateral or medial cortex within the most caudal sites evaluated. Two sites appropriate for sampling with an 8 mm trephine were identified as being centered over the following points: (a) a point 7 mm caudal to the cranial dorsal spine and 7 mm ventral to the tuber sacrale, and (b) a point 7 mm caudal to the cranial ventral spine and 7 mm dorsal to the tuber coxae. Comparison of data obtained from males and females indicated that sampling variation may also be reduced by using dogs of one sex and by preferential use of males.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02411273
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  • 9
    Digitale Medien
    Digitale Medien
    Perspectives on osteoporosis research: Its focus and some insights from a new paradigm (1995)
    Springer
    Calcified tissue international 57 (1995), S. 399-404 
    Details
    ISSN: 1432-0827
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Conclusion (1) Could future osteoporosis research begin to account for the things described in this editorial? (2) Could agencies that give grants to support that research begin to encourage that accounting? (3) Since the FDA guidelines have great influence on what osteoporosis research is done and not done, mitht revisions of the 1994 guidelines try to acknowledge those things?
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00301939
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  • 10
    Digitale Medien
    Digitale Medien
    Studies on the role of 24-hydroxylation of vitamin D in the mineralization of cartilage and bone of vitamin D-deficient rats (1981)
    Springer
    Calcified tissue international 33 (1981), S. 489-497 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Vitamin D ; Vitamin D deficiency ; Cartilage ; Bone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary To test the importance of 24-hydroxylation of vitamin D3 on bone mineralization, rat pups born to vitamin D-deficient females were given either 25-hydroxyvitamin D3 or 24,24-difluoro-25-hydroxyvitamin D3 for 16 days beginning at the time of weaning. Following such treatment analysis of blood samples revealed no detectable 24R,25-(OH)2D3 and 1,25-(OH)2D3 in the rats given the difluoro compound while revealing the expected 24,24-difluoro-25-hydroxyvitamin D3 and 24,24-difluoro-1,25-dihydroxyvitamin D3. The rats given 25-hydroxyvitamin D3 had the expected levels of 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D3, and 1,25-dihydroxyvitamin D3. Following sacrifice at day 17, postweaning bone mineralization and modeling were studied in long bones using histological methods. Bones taken from vitamin D-deficient rats at the beginning and end of the experimental period had lesions typical of rickets. These included wide growth plates, excessive amounts of osteoid, and metaphyseal fibrosis. Following treatment with either 25-hydroxyvitamin D3 or 24,24-difluoro-25-hydroxyvitamin D3, bone mineralization returned to normal. Growth plate widths and the amount of osteoid on bone surfaces were both substantially reduced and to a similar degree in both treatment groups. Normal cartilage core formation and trabecularization of the metaphyseal primary spongiosa were also restored to a similar degree in both groups. In effect, no difference was observed in any bone parameter studied between the 25-hydroxyvitamin D3- and the 24,24-difluoro-25-hydroxyvitamin D3-treated animals. These results provide strong evidence that 24-hydroxylation of the vitamin D molecule plays little or no role in the modeling and mineralization of bone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02409479
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