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  • 1
    Electronic Resource
    Electronic Resource
    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
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1981.tb00976.x
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  • 2
    Electronic Resource
    Electronic Resource
    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
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1981.tb00995.x
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  • 3
    Electronic Resource
    Electronic Resource
    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
    Keywords: Vitamin D ; Vitamin D deficiency ; Cartilage ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409479
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  • 4
    Electronic Resource
    Electronic Resource
    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
    Keywords: Membrane potential ; Electrolyte and protein contents ; Cell pH ; Cyclic AMP and hormonal preparations ; Endosteal bone cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405352
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  • 5
    Electronic Resource
    Electronic Resource
    Bone loss in the Beagle tibia: Influence of age, weight, and sex (1981)
    Springer
    Calcified tissue international 33 (1981), S. 233-238 
    Details
    ISSN: 1432-0827
    Keywords: Osteopenia ; Tibia ; Aging ; Beagles ; Bone mineral analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In a cross-sectional study, 154 Beagles (79 males, 74 females) ranging in age from 14 to 187 months were measured for bone mineral, bone width, and mineral-to-width ratio on the distal shaft of the right tibia using a photon absorptiometer. The measurements were evaluated with regard to age, sex and body weight. The results indicate that males were heavier than females in body weight, with weight being reduced in the older animals of both sexes. When compared on an age basis, males had more mineral, a wider tibia, and a greater mineral-to-width ratio than females. The males and females reach their peak mineral, and mineral-to-width ratio at about 6 years of age and then decline. On a body weight basis, mineral, width and mineral-to-width ratio all increase with increasing body weight, with bone width being the least affected by changes in body weight. The values for females are less than those for males in all parameters with the greatest differences occurring at the greater weights. The only variance from these observations was the greater mineral-to-width ratio in the lighter females. It is concluded that, when examining cortical bone, the Beagle is a model of age-related osteopenia, and body weight is an important consideration when explaining changes in bone mineral.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409442
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  • 6
    Electronic Resource
    Electronic Resource
    Variations in mineral apposition rate of trabecular bone within the beagle skeleton (1981)
    Springer
    Calcified tissue international 33 (1981), S. 583-586 
    Details
    ISSN: 1432-0827
    Keywords: Tetracycline ; Trabecular bone ; Mineral apposition rate ; Bone marrow ; Vascularity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The mineral apposition rate of trabecular bone was determined in several skeletal sites of young adult beagles. Tetracycline derivatives were administered intravenously or orally on 2 separate occasions preceding the day of sacrifice in order to label actively mineralizing bone surfaces. The rate of mineral apposition was calculated by dividing the distance between the 2 tetracycline markers by the time interval between their administration. The lumbar vertebra, proximal humerus, and pelvis, each of which contains red marrow, were found to have a significantly higher (P〈0.001) rate of mineral apposition in trabecular bone than the skeletal sites containing yellow marrow—the proximal ulna and distal humerus. The mean apposition rate in the former 3 sites was 1.3±0.3µm/day, while that in the latter 2 was 0.9±0.2µm/day (uncorrected for plane of sectioning). It is tempting to speculate that this finding may be a consequence of differences in vascularity between red and yellow marrow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409495
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  • 7
    Electronic Resource
    Electronic Resource
    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
    Keywords: Ilium ; Trabecular bone ; Biopsy ; Variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411273
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  • 8
    Electronic Resource
    Electronic Resource
    A quantitative histologic study of bone turnover in young adult beagles (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 203 (1982), S. 31-45 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Thirty-six regions of trabecular bone from two 18-month-old beagles and transilial biopsies of 25 female beagles aged 28-52 months were studied following in vivo double tetracycline labeling. Turnover rate varied from about 20% per year to 200% per year among the 36 regions. It was highest in the vertebral bodies and the proximal humerus, and lowest in the proximal ulna and foot-bones. The mineral apposition rate varied from 0.35 to 1.02 μm/day, with a mean of about 0.7 μm/day, tending to be lower in areas of lower turnover. The specific surface varied from 10.9 to 23.8 mm/mm2 with a mean of 17.5 mm/mm2, tending to be higher in areas of high turnover. Specific surface varied only about twofold around the skeleton, while turnover varied by one order of magnitude. The average annual turnover rate for all trabecular bone in the young adult beagle is estimated at 140% per year. The accuracy of this estimate would be improved by knowing the exact mass of trabecular bone at each site.The annual turnover rate in the ilium of 25 female beagles was 134 ± 94% per year. The iliac trabecular bone turnover rate is two to three times faster in young adult female beagles than in young adult female humans. Using a human to beagle ratio of 1:2.5, the average annual turnover rate for all trabecular bone in the young adult human could be estimated at 40-55% per year. The beagle may be an appropriate model for certain experiments involving the adult bone remodeling system, because it may show a quicker response than humans to various experimental conditions and drugs, due to its faster turnover rate.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092030104
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