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  • Bone  (70)
  • Springer  (70)
  • MDPI Publishing
  • 1975-1979  (70)
  • 1940-1944
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  • Springer  (70)
  • MDPI Publishing
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Year
  • 1
    Electronic Resource
    Electronic Resource
    X-ray diffraction of the calcified tissues inPolypterus (1979)
    Springer
    Calcified tissue international 28 (1979), S. 37-42 
    Details
    ISSN: 1432-0827
    Keywords: X-ray diffraction ; Hydroxyapatite ; Whitlockite ; Fish (Pisces) ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Pyrolyzed scales, fin spines, and bone from the ray-finned bony fishPolypterus (Actinopterygii) showed two mineral phases on X-ray diffraction: hydroxyapatite (HA), Ca5(PO4)3OH, and whitlockite, Ca3(PO4)2. The ratio of HA/whitlockite varied with the structure (scale, spine, bone) within each individual fish. The relative proportions of HA to whitlockite in pyrolyzed samples reflected the Ca/P ratio of the sample. Whitlockite appears after pyrolysis when the Ca/P is lower than 1.67. Among the five fish investigated, for each structure a general trend was noted. The proportion of HA relative to whitlockite increased with size (age) of the fish. Thus the smallest fish, a juvenile, exhibited a low Ca/P mineral in its calcified tissues, whereas the larger fish had progressively more HA and less whitlockite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441216
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  • 2
    Electronic Resource
    Electronic Resource
    On the solid state of bone (1979)
    Springer
    Calcified tissue international 28 (1979), S. 33-36 
    Details
    ISSN: 1432-0827
    Keywords: Infrared, visible light ; Bone ; Collagen ; Apatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Photovoltaic effect (infrared and visible light) is observed in bone and its two major components, collagen and apatite, at room temperature. A dimunition in the magnitude of photovoltage is observed after exposure to ultraviolet light in all the cases. The drift mobility of the charge carriers is obtained by measuring I versus V relationships in sandwich samples and relating them to the permitivity of the medium. Lifetime of the injected carriers is measured in the usual way. The data are consistent with the hypothesis that the effects are due to protonic conduction phenomena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441215
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  • 3
    Electronic Resource
    Electronic Resource
    The calciuria of increased fixed acid production in humans: Evidence against a role for parathyroid hormone and 1,25(OH)2-vitamin D (1979)
    Springer
    Calcified tissue international 28 (1979), S. 233-238 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; PTH ; 1,25(OH)2D ; Acid ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We measured mineral and acid balances, serum iPTH, urinary cAMP/creatinine, and plasma concentrations of 25OHD and 1,25(OH)2D in 7 healthy adults during control conditions and during increased fixed acid production achieved either by the administration of NH4Cl (N=3) or by increased dietary protein intake (N=4). When acid production was increased, the subjects were in positive acid balance and negative Ca balance because of increased urinary Ca excretion. Serum iPTH fell slightly but urinary cAMP and the plasma levels of vitamin D metabolites did not change. We conclude that the accelerated skeletal and urinary losses of Ca that occur when fixed acid production is increased are not contributed to nor compensated for by the parathyroid-vitamin D endocrine systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441241
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  • 4
    Electronic Resource
    Electronic Resource
    Use of a spectrophotometer for radiographic photodensitometry of bone (1979)
    Springer
    Calcified tissue international 28 (1979), S. 103-105 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Photodensitometry, X-ray ; Radiography ; Spectrophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A conventional spectrophotometer was used to do radiographic photodensitometry of bone mass. An experiment to produce osteoporosis in guinea pigs required quantification of changes in bone mass. Lack of a densitometer necessitated finding another method for quantification. The method developed involved using industrial film in a closed X-ray system. Optical density of X-rays was then read in a spectrophotometer at nine femur locations. Highly significant correlations between optical density and femur calcium content and femur dry weight per millimeter were obtained. Histological sections from an animal with low optical density measurements confirmed bone loss by showing decreased cortical width and loss of trabecular bone. In addition to using readily available equipment, this method offers the advantage of being able to detect bone loss in specific areas of the bones. In addition, bones are left intact and can be used for other purposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441227
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  • 5
    Electronic Resource
    Electronic Resource
    Analysis of paramagnetic centers in X-ray-irradiated enamel, bone, and carbonate-containing hydroxyapatite by electron spin resonance spectroscopy (1979)
    Springer
    Calcified tissue international 28 (1979), S. 107-112 
    Details
    ISSN: 1432-0827
    Keywords: ESR ; Bone ; Enamel ; CO3-Apatite ; Paramagnetism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Carbonate-containing hydroxyapatite, enamel, and bone were irradiated by an X-ray and investigated between 77° and 350°K by means of electron spin resonance (ESR) spectroscopy. The ESR spectrum of enamel irradiated at 77°K in vacuum and observed at the same temperature was almost the same as that of the carbonate-containing hydroxyapatite. The temperature dependence of signal intensities confirms a spin-energy exchange between the mineral and organic constituents in bone, but in enamel no or very little spinenergy exchange between the mineral and organic constituents. Considerable similarity among the ESR spectra of enamel, bone, and carbonate-containing apatite was obtained after X-ray irradiation in air at 300°K with both an X-band and a Q-band ESR spectrometer. The Q-band spectrum can be interpreted in terms of two paramagnetic species. One is identified as a CO 3 3− anion radical which has an axial symmetry withg factors of 2.0029 and 1.9972. The other species is found to be centered atg=2.0019.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441228
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  • 6
    Electronic Resource
    Electronic Resource
    Noninvasive measures of bone bending rigidity in the monkey (M. nemestrina) (1979)
    Springer
    Calcified tissue international 27 (1979), S. 109-115 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Bending rigidity ; Disuse atrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The in vivo bending rigidity and bone mineral content of monkey ulnae and tibiae were measured. Bending rigidity in the anteroposterior plane was measured by an impedance probe technique. Forced vibrations of the bones were induced with an electromechanical shaker, and force and velocity at the driving point were determined. The responses over the range of 100–250 Hz were utilized to compute the bending rigidity. Bone mineral content in the cross section was determined by a photon absorption technique. Seventeen male monkeys (Macaca nemestrina) weighing 6–14 kg were evaluated. Repeatability of the rigidity measures was 4%. Bone mineral content was measured with a precision of 3.5%. Bending rigidity was correlated with the mineral content of the cross section,r=0.899. Two monkeys were evaluated during prolonged hypodynamic restraint. Restraint produced regional losses of bone most obviously in the proximal tibia. Local bone mineral content declines 17 to 24% and the average bending rigidity declines 12 to 22%. Changes in bones leading to a reduction in mineral content and stiffness are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441171
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  • 7
    Electronic Resource
    Electronic Resource
    Age-related changes in the density and tensile strength of human femoral cortical bone (1979)
    Springer
    Calcified tissue international 27 (1979), S. 105-108 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Femur ; Strength ; Density ; Age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In order to ascertain whether the intrinsic strength of human bone changes with age or not, we have determined the ultimate tensile strength and density of strips of femoral cortical bone. These femora were collected from cadavers varying in age from 13 to 97 years. The results show that both density and intrinsic strength of bone increase up to about the fourth decade of life and then decrease with age. However, the rate of decrease of strength is greater than that of density. This indicates that the density of bone is not the sole determining factor of its strength, and that some other factors play an important part.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441170
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  • 8
    Electronic Resource
    Electronic Resource
    Anticonvulsant drug-induced osteomalacia: Alterations in mineral metabolism and response to vitamin D3 administration (1979)
    Springer
    Calcified tissue international 27 (1979), S. 13-18 
    Details
    ISSN: 1432-0827
    Keywords: Anticonvulsants ; Calcium ; Vitamin D ; Parathyroid hormone ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Parameters of mineral metabolism were examined in 6 patients with moderately severe anticonvulsant drug-induced osteomalacia. Compared to 15 matched controls, the patients exhibited significantly reduced serum calcium, inorganic phosphate, and 25-hydroxyvitamin D concentration, elevated serum alkaline phosphatase and immunoreactive parathyroid hormone (iPTH) concentration, reduced intestinal47Ca absorption, reduced urinary calcium and increased urinary hydroxyproline excretion, and reduced forearm bone mass. Intestinal absorption of vitamin D3 was normal. Following 4 months of treatment with vitamin D3 (4000 units/day), serum 25-OHD concentration was increased to 3 times mean normal values and all parameters except serum iPTH, urinary calcium excretion, and forearm bone mass were returned to levels not significantly different from normal. Serum iPTH concentration was reduced by 39% (P〈0.05); 24-h urinary calcium excretion rose by 98% (P〈0.001), and forearm bone mass increased by 5.6% (P〈0.05). It is concluded that moderate-dose vitamin D3 supplementation is effective in normalizing parameters of mineral metabolism in this disorder, despite evidence of resistance to the biologic effects of vitamin D.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441155
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of changing hydrogen ion, carbonic acid, and bicarbonate concentrations on bone resorption in vitro (1979)
    Springer
    Calcified tissue international 29 (1979), S. 7-13 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Culture ; Resorption ; Acidosis ; Alkalosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have examined the effects of H+, CO2, and HCO3 − concentrations during metabolic and respiratory acidosis and alkalosis on bone resorption in vitro. Rat fetal bones prelabeled with45CaCl2 were cultured at 2%, 5%, and 10% CO2 for up to 120 h, and the release of45Ca was measured in devitalized bones (non-cell-mediated45Ca release) and in live bones (cell-mediated45Ca release) cultured with or without PTH and 1,25(OH)2D3. Non-cell-mediated mineral loss was linearly related to H+ concentration but not to CO2 or HCO3 − concentration. This effect was observed on both labeled and stable calcium. Over a wide pH range (6.9–7.5) H+, CO2, or HCO3 − concentrations did not influence cell-mediated bone resorption in control or in PTH-and 1,25(OH)2D3-stimulated cultures. However, inhibition of cell-mediated bone resorption was observed at higher or lower pH irrespective of CO2 or HCO3 − concentrations. These observations demonstrate that the bone mineral mobilizing effect of acidosis in vitro is mainly due to the effect of changing H+ concentration on devitalized bone. Effects on cell-mediated bone resorption and hormonal response were observed only at extremes of pH. The effects of H+ were independent of changes in CO2 or HCO3 − concentration and could be responsible for the negative calcium balance and increased urinary loss observed in metabolic acidosis in vivo, but do not explain the reported differences in effects on calcium metabolism between respiratory and metabolic acidosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408049
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  • 10
    Electronic Resource
    Electronic Resource
    Bone fluoride concentrations associated with fluoridated drinking water (1979)
    Springer
    Calcified tissue international 27 (1979), S. 95-99 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Fluoride ; Analysis ; Food ; Age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Recently published bone fluoride values from Iowa are very high compared to earlier reports, suggesting an increase in fluoride intake. Reanalysis of the Iowa specimens shows levels one-fourth those reported by the Iowa laboratory indicating an error in the original report. Seventeen bone specimens, collected from long-term residents of Rochester, New York, drinking 1 ppm F− water, had a mean value of 2085±270 ppm F− on an ashed-weight basis. This value is not significantly different from that predicted by the data of Zipkin et al. in 1958. These data, therefore, do not support the contention that there has been an increase in fluoride intake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441168
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  • 11
    Electronic Resource
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    Bone maturation in the vitamin D, phosphate deficient rat and the response to acid loading (1979)
    Springer
    Calcified tissue international 27 (1979), S. 233-237 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Vitamin D ; Acidosis ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Vitamin D and phosphate deficiency were produced in rats in order (a) to evaluate the degree of bone mineral and matrix maturation using a bromoform/toluene density gradient technique; and (b) to compare the aforementioned bone maturational changes due to vitamin D and phosphate deprivation to those produced with superimposed severe acidosis. Rats were fed a diet deficient in vitamin D and phosphorus (0.2%) from 3 weeks through 7 weeks of age. To examine the additional contribution of dietary calcium, we gave one-half of the animals either a low (0.06%) or high (1.3%) calcium diet. Following the 4 weeks of vitamin D deficiency, one-half of each group was given 1.8% NH4Cl in the drinking water for 4 succeeding days to induce an acute, severe acidosis. The degree of bone maturation was quantitated via bromoformtoulene density gradient fractionation; total mineral and hydroxyproline (collagen) levels were quantitated as well. The vitamin D-deficient rats deprived of adequate dietary phosphate responded by conserving phosphorus, and as a consequence total bone phosphorus levels were maintained within that level for control rats. This conservation was independent of calcium intake but was extremely sensitive to acute acid loading, where a significant reduction in total bone phosphorus was noted. The bone maturational profile obtained from the vitamin D-phosphate deficient rats, however, revealed a significant accumulation of less mature or dense bone collagen and mineral with a corresponding decrease in the most mature or dense moieties. In contrast to the reduction of the total bone phosphorus content by acute acidosis, the skeletal collagen-mineral maturational profile was not significantly affected by the short-term systemic acidosis. The observed retardations in the bone collagen and mineral maturation of the vitamin D-deficient, phosphate-deprived state provide an additional observation which may well relate to the progressive osteopenia documented in states of chronic, mild acidosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441191
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  • 12
    Electronic Resource
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    Changes in proline synthetic and degradative enzymes during matrix-induced cartilage and bone formation (1979)
    Springer
    Calcified tissue international 27 (1979), S. 275-279 
    Details
    ISSN: 1432-0827
    Keywords: Proline ; Cartilage ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Proline biosynthetic and degradative enzymes are unevenly distributed in differentiated mammalian tissues. Activities of the synthetic enzymes are relatively high in collagenous tissues, whereas activities of the degradative enzymes are high in noncollagenous tissues. In order to further characterize tissue-specific proline biosynthesis and degradation, we have determined proline enzyme activities during cartilage and bone formation induced by demineralized bone matrix. We can thus follow temporal changes in enzyme activity in a single tissue as different cell types develop. Ornithine aminotransferase and pyrroline-5-carboxylate reductase have peaks of activity which correlate with maximal type II collagen synthesis by chondrocytes. Both enzymes also are active during bone formation. In contrast, proline oxidase and pyrroline-5-carboxylate dehydrogenase are present at low levels and do not change as new cell types appear. Arginase activity peaks during the first 3 days and then rapidly decreases by the time cartilage and bone formation begin. These observations further substantiate the importance of proline biosynthesis in collagenous tissues. The close correlation between ornithine aminotransferase activity and type II collagen synthesis suggests that the pathway from ornithine to proline may be especially important during formation of type II collagen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441197
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  • 13
    Electronic Resource
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    Disordered mineral metabolism produced by ketogenic diet therapy (1979)
    Springer
    Calcified tissue international 28 (1979), S. 17-22 
    Details
    ISSN: 1432-0827
    Keywords: Anticonvulsant ; Ketogenic diet ; Calcium ; Vitamin D ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Vitamin D and mineral metabolism status was examined in five children maintained chronically on combined ketogenic diet-anticonvulsant drug therapy (KG), and the results compared to those obtained in 18 patients treated with anticonvulsant drugs alone (AD) and 15 normal controls. KG patients exhibited biochemical findings of vitamin D deficiency osteomalacia: decreased serum 25-hydroxyvitamin D (25OHD) and calcium concentrations, elevated serum alkaline phosphatase and parathyroid hormone concentrations, decreased urinary calcium and increased urinary hydroxyproline excretion, and decreased bone mass. Although the KG and AD groups demonstrated similar reductions in serum 25OHD concentration, the KG patients exhibited a significantly greater reduction in bone mass. In response to vitamin D supplementation (5000 IU/day), mean bone mass in the KG group increased by 8.1±0.9% (P〈0.001) over a 12-month period. These results suggest that ketogenic diet and anticonvulsant drug therapy have additive deleterious effects on bone mass and that these effects are partially reversible by vitamin D treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441213
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  • 14
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    The occurrence of chondroitin-6-sulphate in adult human compact bone tissue (1979)
    Springer
    Calcified tissue international 29 (1979), S. 169-171 
    Details
    ISSN: 1432-0827
    Keywords: Glycosaminoglycans ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Compact bone tissue chondroitin sulphate, previously considered to be pure chondroitin-4-sulphate, was isolated from three adult human femoral diaphyses and digested with chondroitinase ABC. Assaying these digests by means of high performance liquid chromatography we could demonstrate that 12 to 14% of the disaccharide residues were 6-sulphated. The 4/6-ratios were also studied in chondroitin sulphate fractions of different molecular size. Slightly increasing amounts of 6-sulphated disaccharides were found with increasing size of the chondroitin sulphates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408073
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  • 15
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    Growth of embryonic chick tibiae in ovo and in vitro: A scanning electron microscope study (1979)
    Springer
    Calcified tissue international 27 (1979), S. 33-40 
    Details
    ISSN: 1432-0827
    Keywords: Chick embryo ; Bone ; Organ culture ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The study describes the ultrastructure of the mineralized portion of chick tibiae from 10 days in ovo to 2 days post-hatch. At 10 days a single mineralized cylinder surrounds the diaphysis. On its outer surface columnar trabeculae join to form ridges parallel to the long axis of the bone. These ridges are covered by another cylinder and form the haversian canals. At 11 days vascular invasion of the marrow cavity occurs and resorption of the endosteal surface begins. This type of periosteal deposition and endosteal resorption is repeated during and subsequent to embryonic development. The mineralized portion of 10-day chick tibiae cultured for 2 days in modified BGJ medium was compared with 10-, 11-, and 12-day tibiae in ovo. Cultured tibiae were similar in length and calcium content to 11-day tibiae in ovo. The form of mineral deposited in ovo and in culture was the same, namely, aggregates of spherical mineral clusters. Differences in culture included the following: (a) few concentric cylinders were deposited as compared with tibiae in ovo; (b) trabeculae were not arranged in rows and ridges in culture; (c) osteocytic lacunae were restricted to bases of trabeculae rather than uniformly distributed as in ovo; and (d) the endosteal surface of tibiae in culture appeared etched.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441158
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  • 16
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    An ultrastructural study of the role of calcification nodules in the mineralization of woven bone (1979)
    Springer
    Calcified tissue international 27 (1979), S. 57-64 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Bone formation ; Calcification ; Calcification nodule ; EM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Osteolathyrism has been used as an experimental model for the study of calcification nodules during the mineralization process. Periosteal exostoses developing in osteolathyrism characteristically have spherical basophilic structures (calcification nodules) in the vicinity of developing bone spicules. In thin sections, the nodules were seen scattered between collagen fibers in the intercellular matrix. Collagen fibers did not appear to be present within the nodules but sometimes were packed just outside them. Matrix vesicles were also present in areas of early mineralization. After EDTA decalcification, the majority of the nodules consisted of a fine granular material surrounded by an electron-dense peripheral zone. The peripheral dense zone was occasionally incomplete in small nodules in areas of early mineralization. An electron-dense central area could be observed in the center of the nodules. Evidence has been presented indicating that the calcification nodules arise from smaller mineralization foci, presumably matrix vesicles. The calcification nodules enlarge to approximately 1.0 µm in size, at which point development is slowed or halted allowing the formation of the peripheral dense zone. Although coalescence of nodules was observed, this was more a random event. The further mineralization of the trabeculae was achieved by the calcification of the collagen fibers. The mineralized trabeculae reflected this pattern of nodular and collagenous calcification. It is suggested that this pattern of calcification is characteristic of rapidly developing woven bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441162
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  • 17
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    Distribution of the perilacunar hypomineralized areas in cortical bone from patients with familial hypophosphatemic (vitamin D-resistant) rickets (1979)
    Springer
    Calcified tissue international 27 (1979), S. 101-104 
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    ISSN: 1432-0827
    Keywords: Bone ; Rickets ; Hypophosphatemia ; Microradiography ; D-resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The perilacunar areas of low mineral density in microradiographs from cortical bone of patients with hypophosphatemic (vitamin D-resistant) rickets are not evenly distributed throughout the bone tissue. Their frequency and distribution were determined in bone from 9 patients with this disease. It was found that the lesion was more frequent in haversian bone than in interstitial bone, and along the inner circumference of growing haversian systems as compared with the outer circumference. These findings indicate that the lesion is the result of retarded mineralization, and that mineralization slowly proceeds in these areas as the bone becomes older. A relatively high frequency of the lesion was also found in osteons with an elliptical cross section along the long axis of the ellipse. The cause of the abundance of the lesion at these sites is not clear, but it is possible to explain the uneven distribution in elliptical osteons by assuming an unequal rate of bone formation in these structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441169
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  • 18
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    Effect of carbon dioxide and various oxygen tensions on the respiratory activity of bone (1979)
    Springer
    Calcified tissue international 27 (1979), S. 165-169 
    Details
    ISSN: 1432-0827
    Keywords: Oxygen uptake ; Bone ; Oxygen tension ; Carbon dioxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The present study was carried out to determine the influence of carbon dioxide and oxygen tension on the respiratory activity of bone cells in mouse calvaria in vitro. Five-day-old mouse calvaria were removed aseptically and incubated individually for 1 h at 37° C in a closed reaction chamber containing 1.5 ml of tissue culture medium made up of 60% horse serum in Gey's solution containing 100 unit/ml penicillin and 100µg/ml streptomycin. Before the calvaria were added, the medium in the incubation chamber was equilibrated with 10%, 20%, 30%, or 50% oxygen balanced with nitrogen. The effect of CO2 on oxygen utilization by the calvaria was determined by incubating the calvaria in a medium previously equilibrated with either 50% O2 balanced with N2 or 50% O2 and 5% CO2 balanced with N2. At each oxygen tension, the rate of oxygen utilization by the calvaria was measured polarographically by a Clark oxygen electrode. The results showed that the rate of oxygen uptake of bone increased as the oxygen tension increased and carbon dioxide stimulated significantly the rate of oxygen utilization by the bone cells. In view of the previous reports that both carbon dioxide and oxygen tension are implicated in the process of bone resorption, it is suggested that these two factors may affect bone resorption by influencing the oxygen utilization by bone cells and ultimately controlling their energy metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441180
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  • 19
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    Radioautographic visualization of3H-fucose incorporation into glycoprotein by osteoblasts and its deposition into bone matrix (1979)
    Springer
    Calcified tissue international 27 (1979), S. 177-185 
    Details
    ISSN: 1432-0827
    Keywords: Calcification ; Bone ; Glycoprotein ; Golgi ; Osteoblasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The elaboration of bone matrix glycoprotein by osteoblasts of alveolar bone was investigated by radioautography after the intravenous injection of3H-fucose into young rats. At selected times after injection, animals were sacrificed by intracardiac perfusion and demineralized specimens were prepared for light and electron microscope radioautography. At 5 and 10 min after injection, when the blood fucose level was high, silver grains were restricted to the spheroidal and cylindrical saccules of the Golgi apparatus. At 20 min membrane-limited secretory granules were also labeled. By 35 min, the blood fucose level had dropped and silver grains were detected over the apical cortical cytoplasm, in association with secretory granules located therein. Some grains were present over osteoblast processes and the adjacent prebone matrix. By 4 h most of the silver grains had left the cell. At that time they were observed over prebone, adjacent to osteoblast processes, as well as over the prebone-bone junction where a distinct band of label was noted. In demineralized preparations an electron-dense granular material was present at the prebone-bone junction in association with collagen fibrils. These findings provide evidence that osteoblasts in alveolar bone synthesize fucose-containing glycoprotein and indicate that the addition of3H-fucose occurs in the Golgi apparatus. The glycoprotein passes to the apical cortical cytoplasm by way of membrane-limited secretory granules, is exteriorized, and accumulates at the site where prebone transforms into bone (the prebone-bone junction). Since this is also the site of the calcification front, the deposition of labeled glycoprotein may be related to the deposition of bone mineral.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441182
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  • 20
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    Bone metabolism, parathyroid hormone, and calcitonin in paraplegia (1979)
    Springer
    Calcified tissue international 27 (1979), S. 199-204 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Parathyroid hormone ; Calcitonin ; Osteoporosis ; Paraplegia ; Hydroxyproline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In paraplegia, osteoporosis below the neurological lesion occurs early after the spinal cord affection. The serum levels of parathyroid hormone (PTH) and calcitonin (CT), using a radioimmunoassay for the measurement of immunoreactivity, were studied in 12 paraplegic patients for 9 months following onset. Serum Ca and P levels, urinary hydroxyproline excretion, and the kinetic metabolic clearance of45Ca have also been measured. P and immunoreactive (i) CT levels were found the highest at the beginning of the observation and progressively decreased with time. Ca and iPTH serum levels varied inversely with time, the highest level of Ca and the lowest level of iPTH being recorded at the third month following the paraplegia. Mean values of Ca, iPTH, and iCT were in the normal range throughout the study. P levels were increased during the first 3 months. Hydroxyprolinuria was also high and45Ca kinetics showed increased values of Vt, Vo+, and Vu. These parameters indicate a high degree of bone turnover. The results were consistent with the assumption that PTH is not responsible for the increased resorption of bone in paraplegia. Likewise, a deficiency of CT does not seem to be responsible for this bone resorption. These endocrine modifications could be secondary to an increase in the calcium flux from bone to blood and resulting from bone destruction as attested by the increase of urinary calcium and urinary hydroxyproline excretion.
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    URL: http://dx.doi.org/10.1007/BF02441186
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    Effects of osteoclast activating factor from human lymphocytes on cyclic AMP concentrations in isolated mouse bone and bone cells (1979)
    Springer
    Calcified tissue international 28 (1979), S. 23-32 
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    ISSN: 1432-0827
    Keywords: Bone ; Bone cells ; Cyclic AMP ; Osteoclast activating factor ; Lymphokine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Osteoclast activating factor (OAF) is a lymphokine which may participate in the pathologic destruction of bone observed in a number of disorders. In the current studies, we investigated the action of OAF on cAMP accumulation by bones and isolated bone cells in culture. OAF was shown to stimulate accumulation of cAMP in mouse cranial bones at doses between 1 and 1000 ng/ml. Stimulation of bone resorption was observed in bones treated with the same doses of OAF. In order to investigate the cell types responsible for cAMP responses to OAF, we isolated bone cells and grew them in monolayer culture. The cells were isolated by a variety of techniques which separate bone cells into two types of parathyroid hormone (PTH)-responsive populations: (a) cells derived from the periosteal regions of the bone, which also respond to calcitonin with increases in cAMP; and (b) cells derived from the matrix, which do not respond to calcitonin. OAF caused elevation of cAMP levels in both the periosteum-derived cells and the matrix-derived cells. The magnitudes and time courses of OAF effects in these populations resembled the effects previously reported for PTH in the same populations. OAF stimulated adenyl cyclase in both types of cell populations, but did not produce significant changes in cAMP phosphodiesterase activity. OAF differed from PTH in that its effects on cAMP accumulation decreased sharply at supramaximal doses in both bone and isolated cells, especially in the matrix-derived populations. Bone resorption did not decrease as markedly as did cAMP accumulation at high doses of OAF, suggesting that cAMP accumulation and resorption could be dissociated under some conditions. These results indicate that OAF has effects on cAMP production in the same cell populations as PTH, and suggest that OAF could modify not only resorption but also formation of bone in vivo. OAF may exert its effects on bone by means of cAMP-dependent mechanisms, but more data will be necessary to establish this unequivocally. The observed differences between OAF and PTH may be of relevance in the mechanism and treatment of pathologic bone destruction in vivo.
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    URL: http://dx.doi.org/10.1007/BF02441214
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    Effects of measuring system parameters on the frequency dependence of strain-related potentials in bone (1979)
    Springer
    Medical & biological engineering & computing 17 (1979), S. 471-475 
    Details
    ISSN: 1741-0444
    Keywords: Bone ; Strain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Specimens of dry human cortical bone of a disc form were subjected to sinusoidal loading under controlled conditions. The results show a nonlinear increase of the measured peak potential with frequency which reaches a limiting value at about 200 Hz. The analysis, which is based on the circuit representation proposed previously by Shamos, indicates that such a behaviour can be attributed to the measuring circuit parameters. It was found that some relevant results can be interpreted qualitatively by similar analysis.
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    URL: http://dx.doi.org/10.1007/BF02447060
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    Selective stimulation of net calcium efflux from chick embryo tibiae by parathyroid hormone in vitro (1978)
    Springer
    Calcified tissue international 25 (1978), S. 227-232 
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    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Bone ; Calcium ; Chick embryo ; Organ culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The purpose of this study was to measure in an in vitro system the movement of Ca and phosphate (Pi) out of bone when treated with parathyroid hormone (PTH). Tibiae from 13-day chick embryos were incubated for up to 8 h in a defined medium containing 1.8 mM Ca. Medium samples were collected every 2 h and were analyzed for Ca, Pi and lactate. Net effluxes from the bones were calculated. When bones were incubated with PTH in the medium (1 U/ml), net Ca efflux was increased 44, 60 and 100% at 4, 6 and 8 h, respectively. At no time was net Pi efflux affected by the hormone. The well known PTH-stimulated lactate production was not seen until 8 h. Lower doses of PTH (0.1 and 0.3 U/ml) were also effective. Comparing PTH (1 U/ml) responsiveness at higher (2.2 mM) and lower (0.9 mM) medium Ca concentrations, showed that with 2.2 mM Ca no increased Ca efflux was seen, while with 0.9 mM Ca significant elevation in medium Ca occurred 2 h sooner than in the experiments using 1.8 mM Ca. In another experiment, varying the medium Pi level from 1 to 2 mM had no effect on the Ca response to PTH. In neither experiment was Pi release affected by PTH. The results of this study have led to the following conclusions: (1) PTH acts on bone to cause an early dose related increase in net Ca efflux; (2) the effect is specific for Ca, since it is not accompanied by an increased Pi efflux, and may be saturated by raising the medium Ca level; and (3) PTH-stimulated Ca efflux in this system is not correlated with, and is probably not a result of increased lactate production.
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    URL: http://dx.doi.org/10.1007/BF02010774
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    Oestrogen binding proteins in bone cell cytosol (1978)
    Springer
    Calcified tissue international 25 (1978), S. 249-254 
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    ISSN: 1432-0827
    Keywords: Bone ; Oestrogens ; Oestrogen receptors ; Binding proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Attempts were made to demonstrate the presence of specific oestrogen binding proteins (“receptors”) in bone cells. High speed cytosol preparations of bone were incubated with several concentrations of radioactive oestradiol alone and with radioactive oestradiol in the presence of a specific antioestrogen, Nafoxidine. Separation of bound and free oestradiol was carried out by dextran coated charcoal treatment and by sucrose gradient ultracentrifugation. Several types of bones likely to be oestrogen-sensitive were investigated: human femoral heads, human phalanx, rat and rabbit calvaria, humeri and femora of female rats. In all experiments we were unable to demonstrate the presence of specific oestrogen receptors in bone cell cytosol indicating that the direct effect of oestrogens on bone, if present, is not mediated by specific oestrogen receptors.
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    URL: http://dx.doi.org/10.1007/BF02010778
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    Mechanism of osteoclastic bone resorption: A new hypothesis (1978)
    Springer
    Calcified tissue international 26 (1978), S. 81-84 
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    ISSN: 1432-0827
    Keywords: Osteoclasts ; Bone ; Resorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Osteoclastic bone resorption involves the solubilization of the mineral salts and the degradation of noncollagen bone matrix and collagen fibrils. As no recognizable collagen fibrils have ever been reported within cytoplasmic vacuoles in osteoclasts, it is generally assumed that the collagen fibrils are digested extracellularly in the resorption zone. The extent to which lysis occurs extracellularly and whether or not the osteoclasts phagocytose the degradation products remain to be established. In the present communication, a hypothesis is presented suggesting the possibility that osteoclastic resorption of bone involves the participation of two different cell types. According to this hypothesis, osteoclastic bone resorption is initiated by osteoclasts that demineralize areas of bone and degrade noncollagen bone matrix. After the osteoclasts have moved away or become partially detached from the demineralized site, the exposed collagen fibrils are phagocytosed by mononuclear, fibroblast-like or monocyte-derived cells.
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    Scanning electron microscope study of separated calcospherites from the matrices of different mineralizing systems (1978)
    Springer
    Calcified tissue international 26 (1978), S. 47-49 
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    ISSN: 1432-0827
    Keywords: Matrix vesicles ; Calcospherites ; Mineralization ; Bone ; Dentin ; Cartilage ; SEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Mineral particle cluster, corresponding to calcospherites or matrix vesicle-initiated clusters in calcifying cartilage and dentin and to collagen bundle-related mineralization in lamellar bone, have been isolated from NaOCl solutions used to dissolve the organic matrix in preparation of anorganic mineralizing fronts for scanning electron microscopy.
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    URL: http://dx.doi.org/10.1007/BF02013233
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    Surface area of dental enamel, bone, and hydroxyapatite: Chemisorption from solution (1978)
    Springer
    Calcified tissue international 26 (1978), S. 139-142 
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    ISSN: 1432-0827
    Keywords: Chemisorption ; Surface area ; Hydroxyapatite ; Bone ; Enamel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The surface areas of three different samples of hydroxyapatite, samples of deproteinized bone, and samples of whole and deproteinized enamel were determined by adsorption of an adduct (the diglycidyl ether of bisphenol A with N-phenylglycine) from methylene chloride solution. In all cases, the surface areas of these samples agree well with those obtained by the BET (N2) method.
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    URL: http://dx.doi.org/10.1007/BF02013248
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    Radiogenic free radicals as molecular probes in bone (1978)
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    Calcified tissue international 25 (1978), S. 37-43 
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    ISSN: 1432-0827
    Keywords: ESR ; Radiation free radicals ; CO3-Apatites ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Exposure of bone mineral to X-rays generates free radicals. These are usually very labile, but can be stabilized at liquid nitrogen temperatures for study by electron spin resonance spectroscopy. The free radicals thus detected in the present study included one with resonances arising from an electron excess center and 2 species with electron-deficit centers: a phosphate anion radical and a radical associated with carbonate. Each of these radicals seemed to be located chiefly at the mineral surface and was sensitive to the surface environment. Presence of an organic phase, as in whole bone, modified free radical production in a manner that suggests interference with the formation of electron deficit centers. Comparison with other synthetic minerals suggests that precipitated carbonateapatites are good models for bone mineral.
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    URL: http://dx.doi.org/10.1007/BF02010749
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    A bone resorbing substance from bovine serum albumin (brA) (1978)
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    Calcified tissue international 25 (1978), S. 233-240 
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    ISSN: 1432-0827
    Keywords: Bone ; Bone resorption ; Albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A fraction (brA), which causes resorption of fetal rat bones in vitro, has been concentrated from bovine serum albumin by anion exchange column chromatography on DEAE Sephadex. This active fraction has also been prepared using DEAE Sephadex A-50 by a batch method with a 0.09M NaCl, 0.1M TRIS buffer, pH 8.35. BrA was 10–30 times more potent than the original albumin. The retained material, which constitutes the bulk of the protein and has less activity than the original albumin, elutes with 0.45M NaCl. Similar treatment of serumα,β or γ globulins does not yield brA. Further enhancement of the bone resorbing activity of brA can be obtained with (NH4)2SO4 fractionation or extraction with CH3OH∶CHCl3. Heating at 55° C for 2 h or at 100° C for 10 min does not affect the activity; overnight incubation with protease destroys the bone resorbing effect. The bone resorbing activity is not removed by dialysis and does not correlate with the protease activity of the fraction. The action of brA is inhibited by 3 mM PO4, 1 μg/ml calcitonin or glucagon, 10−7 M dexamethasone or 0.02 μg/ml actinomycin D. The bone resorbing activity of brA is partially inhibited by 10−7–10−5 M indomethacin. PTH did not elicit bone resorption when added to cultures incubated in chemically defined medium supplemented with 0.1 mg/ml brA. However, brA did not inhibit PTH-induced resorption.
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    URL: http://dx.doi.org/10.1007/BF02010775
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    Plasma disappearance of rabbit α2 HS-glycoprotein and its uptake by bone tissue (1978)
    Springer
    Calcified tissue international 26 (1978), S. 155-161 
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    ISSN: 1432-0827
    Keywords: Plasma protein ; Glycoprotein ; Bone ; Glucosamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Plasmaα 2HS-glycoprotein is specifically accumulated in calcified tissues. In the present studies this glycoprotein was isolated from plasma and after iodination with iodine-125 was injected intravenously into young rabbits. The tissue distribution and plasma disappearance rate of this radioactively labeled material were determined. Of the various tissues studied, bone showed the greatest retention of labeled glycoprotein expressed as percentage of the injected dose per gram tissue relative to the plasma content. The rate of loss of iodinatedα 2HS-glycoprotein from plasma was similar to that ofα 2HS-glycoprotein labeled endogenously by using14C-glucosamine or3H-glucosamine. The uptake of exogenously labeled3I-α 2HS-glycoprotein into bone tissue expressed as a percentage of the injected dose was similar to that of endogenously labeled14C-α 2HS-glycoprotein. These results suggest that the125I-labeled material can be used to study further the metabolism ofα 2HS-glycoprotein by bone tissue.
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    URL: http://dx.doi.org/10.1007/BF02013251
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    Effect of sex steroids on bone collagen synthesis in vitro (1978)
    Springer
    Calcified tissue international 25 (1978), S. 105-110 
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    ISSN: 1432-0827
    Keywords: Progesterone ; 17β estradiol ; Testosterone ; Tissue culture ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Although sex steroids are known to affect skeletal metabolism, their effects on bone collagen synthesis have not been studied. We have examined the direct effects of progesterone, 17β estradiol, testosterone, 5α dihydrotestosterone and dehydroepiandrosterone on bone collagen and noncollagen protein synthesis in cultures of calvaria obtained from 21-day fetal rats. Bones were incubated for 24 to 168 h and3H-proline was added for the last 2 h of culture. Incorporation of the label into collagenase-digestible protein (CDP)1 and noncollagen protein (NCP) was determined using repurified bacterial collagenase. Progesterone caused a dose dependent inhibition of the labeling of CDP at concentrations of 3×10−7 M to 10−5 M after 96 h of culture. A smaller inhibitory effect was observed on NCP. The inhibitory effect was slow in onset and persisted when bones were incubated for 48 h with progesterone and then transferred to control medium for 48 h. Progesterone also inhibited the incorporation of3H-thymidine and3H-uridine into fetal rat calvaria. After 24 h of culture, 17β estradiol and testosterone had no effects on the labeling of CDP and NCP. After 96 h, 17β estradiol had a small and inconsistent stimulatory effect on the labeling of CDP but testosterone had no effect. Neither hormone altered the inhibitory effects of parathyroid hormone, cortisol and progesterone. Dihydrotestosterone and dehydroepiandrosterone had no effects after 24 h and 96 h of culture. 17β estradiol, testosterone and dihydrotestosterone did not affect the incorporation of3H-uridine or3H-thymidine into fetal rat calvaria. Our studies indicate that progesterone is an inhibitor of bone collagen synthesis and estrogens and androgens are not major regulators of bone formation in vitro.
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    Effect of mithramycin on boneβ-glucuronidase and resorption (1978)
    Springer
    Calcified tissue international 26 (1978), S. 209-213 
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    ISSN: 1432-0827
    Keywords: Mithramycin ; Bone ; β-Glucuronidase ; KT medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Mithramycin suppresses bone resorption. Its effect on the synthesis and release of β-glucuronidase (a referent for lysosomal enzymes) in mouse calvarial explants was studied in an in vitro culture system. A newly described medium (designated as KT medium) was introduced in this specific study. Mithramycin initially inhibited the release of β-glucuronidase into the medium and resulted in an ultimate accumulation of this enzyme in the bone. These results suggest that inhibition of bone resorption by mithramycin may be attributed to interference in release of lysosomal enzymes from bone cells.
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    Quantitative histology of bone: A computerized method of measuring the total mineral content of bone (1978)
    Springer
    Calcified tissue international 26 (1978), S. 85-89 
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    ISSN: 1432-0827
    Keywords: Bone ; Histology ; Microradiography ; Densitometry ; Computer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A comparatively simple quantitative method for assessing bone morphology has been evolved. Microradiographs of thin sections of mandible have been scanned with a Joyce-Loebl double beam recording microdensitometer with a scanning autodensidater attachment, using a white beam. For each image the optical densities for all the pixels (picture elements) were divided into 10 groups. The limits of the division were fixed by the maximum and minimum densities occurring within the image. A computer generated map was produced which indicated the spatial distribution of the pixels within each group to which an arbitrarily chosen shading was attached. The number of pixels within each group is also shown on the map. The computer map was compared with the photomicrograph and, where necessary, the original section. The fractional area of hard tissue was then readily determined using the numerical values of each group of pixels.
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    The effect of growth retardation and of osteomalacia on the uptake of albumin by bone (1978)
    Springer
    Calcified tissue international 25 (1978), S. 29-35 
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    ISSN: 1432-0827
    Keywords: Albumin ; Bone ; Growth retardation ; Osteomalacia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary 125I-labeled rat albumin injected intravenously into rats was taken up by growing bone. Some of this radioactive albumin could be removed from bone by washing with saline, the proportion so removed decreasing from 82.5% at 1 day to 7.4% at 8 days. Both the total radioactivity, and that remaining in bone after saline wash, were reduced when growth was slowed by alteration or restriction of the diet. Although the amount of125I albumin in rachitic bone was reduced, autoradiography showed that radioactivity was present in rachitic osteoid. Immunoprecipitation using anti-rat-albumin serum showed that about half of the radioactivity released from normal bone by EDTA was still attached to albumin. These results suggest that albumin plays some part in the growth of bone.
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    The effect of fluoride on bone of rats fed diets deficient in calcium or phosphorus (1977)
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    Calcified tissue international 22 (1977), S. 9-17 
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    ISSN: 1432-0827
    Keywords: Bone ; Fluoride ; Calcium ; Phosphorus ; Mechanical Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Four groups of weanling rats were fed for 2 weeks on a diet sufficient or insufficient in calcium and/or phosphorus. Each group was divided into four subgroups which were offered distilled water supplemented with 0, 50, 75, or 150 ppm fluoride. High levels of fluoride in drinking water inhibited weight gain. This inhibition was less in rats deficient in phosphorus than when normal-phosphorus diets were offered. At a low level, fluoride was without any effect on bone ash, thickness of femoral cortical bone, and mechanical strength, as measured by maximal load, ultimate stress to breaking, and limit of elasticity. Modulus of elasticity was decreased. At higher levels fluoride tended to decrease most of these parameters, except in rats deprived of both calcium and phosphorus. The effect of fluoride was modified by lack of dietary calcium and/or phosphorus and appeared to be weaker in rats deficient in these nutrients. Lack of dietary calcium and/or phosphorus decreased bone strength more than did fluoride content of water and of bone mineral. Concentration of bone ash and thickness of femoral cortical bone were closely correlated with parameters of mechanical strength.
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    A model-independent comparison of the rates of uptake and short term retention of47Ca and85Sr by the skeleton (1977)
    Springer
    Calcified tissue international 22 (1977), S. 183-189 
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    ISSN: 1432-0827
    Keywords: Calcium ; Strontium ; Bone ; Mathematical modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract 1. A method has been devised for comparing the impulse response functions of the skeleton for two or more boneseeking tracers, and for estimating the contribution made by measurement errors to the differences between any pair of impulse response functions. 2. Comparisons were made between the calculated impulse response functions for47Ca and85Sr obtained in simultaneous double tracer studies in sixteen subjects. Collectively the differences between the47Ca and85Sr functions could be accounted for entirely by measurement errors. 3. Because the calculation of an impulse response function requires fewera priori assumptions than other forms of mathematical analysis, and automatically corrects for differences induced by recycling of tracer and non-identical rates of excretory plasma clearance of tracer, it is concluded that differences shown in previous in vivo studies between the fluxes of*Ca and*Sr into bone can be fully accounted for by undetermined oversimplifications in the various mathematical models used to analyse the results of those studies.85Sr is therefore an adequate tracer for bone calcium in most in vivo studies.
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    An x-ray diffraction investigation of age-related changes in the crystal structure of bone apatite (1977)
    Springer
    Calcified tissue international 22 (1977), S. 219-226 
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    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Bone ; X-ray Diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Evidence relating to the existence of crystalline bone mineral in vivo is considered, and bone apatite crystal structure investigated using an x-ray powder diffraction technique. Specimens of femoral compacta excised post-mortem from male and female subjects ranging from 3 1/2 years to 87 years of age have been studied. Values of the ratio c/a of bone apatite crystal cell axes for females are significantly higher (p〈0.05) than for males. Moreover, significant change of c/a with age is observed for males (p=0.0005) but not for females (p=0.30). Differences in c/a are interpreted as indicating substitution of constituent ions in the bone apatite crystals.
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    Isolation of osteoclasts by velocity sedimentation at unit gravity (1977)
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    Calcified tissue international 22 (1977), S. 303-313 
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    ISSN: 1432-0827
    Keywords: Osteoclasts ; Sedimentation ; Isolation ; Cells ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A method is presented for separating osteoclasts from the heterogeneous population of bone and marrow cells. Cell suspensions were prepared from femora of young rabbits by mechanical dispersion. The starting cell suspension typically contained only 1.0%±0.5 osteoclasts. Following an initial 45 min of unit gravity sedimentation in a lucite chamber osteoclasts were primarily distributed in fractions 2–5. A second 45-min sedimentation of these pooled fractions yielded cell suspensions containing greater than 30% osteoclasts (as much as a 50-fold increase over starting percentages). Linear scan analysis, however, revealed that osteoclasts accounted for 73.14%±0.58 of the cell colume. Subsequent in vitro experiments demonstrated linear incorporation of3H-leucine into TCA precipitable protein for cells comprising the osteoclast fraction. Concomitant radiautographs revealed radioactive label in isolated osteoclasts.
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    Bone mineral content in the forearm after fracture of the upper limb (1977)
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    Calcified tissue international 22 (1977), S. 329-331 
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    ISSN: 1432-0827
    Keywords: Bone ; Fracture ; Mineral
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The bone mineral content was measured by gamma absorptiometry in patients who had sustained fractures of the upper limb. Measurements were taken on the shafts of the forearm and in the trabecular bone immediately proximal to the wrist. Fractures of the surgical neck of the humerus and fractures of the shaft of the humerus did not significantly influence the bone mineral content of the ipsilateral forearm. Fracture of the radius and the ulna, however, caused a 15% loss of the bone mineral content in the trabecular bone proximal to the wrist, whereas the mineral content on the shafts of the fractured forearms increased or decreased depending on the fracture site. The findings suggest that measurements of bone mineral content of the forearm are not necessarily invalidated if there has been a fracture of the same limb. Only if the forearm itself is fractured should measurements on this site be avoided.
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    Initial studies on the crystallinity of the mineral fraction and ash content of isolated human and bovine osteons differing in their degree of calcification (1977)
    Springer
    Calcified tissue international 23 (1977), S. 7-11 
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    ISSN: 1432-0827
    Keywords: Electron spin resonance ; Crystallinity ; Bone ; Osteons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Several groups containing 10–15 isolated osteons differing in their degree of maturity were analysed. Samples were isolated from undecalcified human and bovine bone sections. The crystallinity coefficient, defined as the ratio of the number of radiation-induced paramagnetic defects in the crystalline lattice of hydroxyapatite to the total ash content, was calculated. The results were compared with measurements performed on fragments of total cortical bone, primary periosteal bone, and inner circumferential lamellar bone. The results show a higher crystallinity of fully calcified osteons as compared with that found at the initial stage of calcification. No differences in the ash content were observed between human osteons, from different stages of calcification evaluated morphologically and by X-ray absorption. These differences were evident when bovine osteons differing in their stage of calcification were compared. Human fully calcified osteons contain 60% ash and their crystallinity coefficient is 52.1. Human osteons at the initial stage of calcification contain 57% ash and their crystallinity coefficient is 40.6. The same parameters for fully calcified bovine osteons and for bovine osteons at the initial stage of calcification are 59% ash, 62.6 crystallinity coefficient and 46% ash, 43.0 crystallinity coefficient, respectively.
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    Matrix vesicles in newly synthesizing bone observed after ultracryotomy and ultramicroincineration (1977)
    Springer
    Calcified tissue international 23 (1977), S. 185-188 
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    ISSN: 1432-0827
    Keywords: Matrix vesicles ; Bone ; Ultracrytomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Matrix vesicles were observed in femurs of 8-day-old chick embryos prepared by ultracryotomy. Some of the sections were subjected to ultramicroincineration. The unfixed tissues never came into contact with solutions, and thereby artifacts due to dissolution, redistribution, or rearrangement of the mineral constituents were avoided. In the osteoid, electron dense objects with the size and appearance of matrix vesicles were seen, although limiting membranes were not visible. After ultramicroincineration the vesicles were observed to contain small crystals and a less dense amorphous mineral material which may be the precursor of bone mineral. In addition, a ring of ash enclosed the crystalline and amorphous mineral and appeared to occupy the position of the vesicle membrane as seen in conventionally prepared material.
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    On the state of anionic groups of demineralized matrices of bone and dentine (1977)
    Springer
    Calcified tissue international 22 (1977), S. 275-284 
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    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Collagen ; Dentine ; Phosphoprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Calcium-binding and biochemical studies have been applied to characterize the state of the carboxylate and protein-bound phosphate groups in the EDTA-demineralized matrices of rat bone and dentine. The organic phosphate and carboxylate content of demineralized bone is virtually identical to that of purified steer skin collagen whereas demineralized dentine has a significantly higher phosphate and carboxylate content, presumably due to the presence of an acidic non-collagenous phosphoprotein. Two classes of calcium-binding sites can be detected in demineralized bone, demineralized dentine, and purified, reconstituted collagen. The number of strong calcium-binding sites correlates with the number of protein-bound phosphate groups. Depending on the preparative procedure, seven to nine such sites (per collagen molecule) are present in dentine, and one to two in the purified reconstituted collagen and in bone. The binding constant for the dentinal sites (1.1×104 M−1), however, is 20 times greater than that for bone or reconstituted collagen fibrils from skin. We tentatively conclude that the strong calcium-binding site in bone and reconstituted collagen is of the form protein-PO 4 − Ca++ whereas in dentine it is of the form the weak binding sites in bone and dentine are of the form protein-COO-Ca++; and that approximately 160 of the 217 carboxylate groups of the collagen molecules of dentine or bone are present as electrostatic linkages of the form protein-COO−+H3N-protein.
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    Strain related electrical potentials recorded in vitro and in vivo (1977)
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    Calcified tissue international 22 (1977), S. 315-327 
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    ISSN: 1432-0827
    Keywords: Bone ; Bioelectricity ; Strain ; Locomotion ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Using wet dead specimens it was possible to show that the size and form of strain-related electrical potentials on the surface of sheep radii were related both to the amount of strain, and the strain rate, over the range of these recorded during locomotion. Using the same electrode and amplifier system in vivo changes in surface strain and surface charge were recorded from the radius of three sheep during locomotion. During slow locomotion electrical changes were negligible. At medium speed they were most variable, and profoundly influenced by small alterations in the timing and pattern of strain change. When locomotion was fast the electrical waveform reflected fairly faithfully the changes in strain on the bone surface.
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    Cortical bone remodeling in normal rat (1977)
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    Calcified tissue international 23 (1977), S. 161-170 
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    ISSN: 1432-0827
    Keywords: Bone ; Growth ; Rat ; Remodeling ; Tetracyclines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Cortical bone remodeling along the femur diaphysis was determined in normal female rats (Sprague-Dawley) with the tetracycline technique. Three segments on the cortical bone circumference (the anterolateral, the medial, and the posterior) were found to be most suitable for the study of the remodeling process. Oxytetracycline was administered at age 60 and 75 days, and groups of animals were killed at age 75, 85, 95, and 105 days. The accumulated endosteal growth during age 60 to 75 days in the anterolateral segment was found to increase uniformly in the distal direction along the femur diaphysis. A method is described where this accumulated endosteal growth is used. This method eliminates the use of calipers to determine the section level and makes it possible to study comparable sections even after varying periods of time. The proximal part of the diaphysis showed periosteal apposition in all three segments. The periosteal apposition turned into resorption in the distal part of the diaphysis in the anterolateral and medial segments, whereas the periosteal appsition increased in the posterior segment. The endosteal growth increased in the distal direction in the anterolateral and medial segments. Irregular OTC bands made measurements of endosteal remodeling in the posterior segment impossible. The cortical width decreased in the distal direction along the femoral shaft. Comparison between the different age groups is described and also the relation between the accumulated endosteal growth and the diameter of the medullary cavity.
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    Preliminary studies on the binding of plasma albumin to bone tissue (1977)
    Springer
    Calcified tissue international 23 (1977), S. 303-305 
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    ISSN: 1432-0827
    Keywords: Albumin ; Bone ; Hydroxyapatite ; Plasma protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The extractability of125I-labelled plasma albumin from bone pieces and from powdered bone has been compared after both in vivo and in vitro incorporation. The results show that albumin is more readily extracted from bone pieces than from bone powder which implies that tissue disruption exposes additional protein adsorption sites. It is suggested that incorporation of plasma albumin into calcified matrix during bone formation occurs mainly as a result of its strong interaction with bone mineral.
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    URL: http://dx.doi.org/10.1007/BF02012801
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    Density and composition of trabecular and cortical bone in perinatally irradiated beagles with chronic renal failure (1977)
    Springer
    Calcified tissue international 24 (1977), S. 99-104 
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    ISSN: 1432-0827
    Keywords: Bone ; Density ; Composition ; Renal osteodystrophy ; Dogs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Bone density and composition were studied in trabecular and cortical bone from control 2 and 4 year old beagles and those which had various degrees of renal failure as a result of perinatal irradiation. Changes in the two types of bone were qualitatively similar but consistently greater in trabecular bone. In a group identified as markedly uremic, the decrease (P〈0.025) from control levels in specific gravity was about 4 times greater in trabecular than in cortical samples. The decrease (P〈0.025) in grams of ash/ml was 9% in trabecular bone and 2% in cortical bone. These changes were associated with an increase (P〈0.001) in water content and, on a percent by volume basis, approximately equal decreases in ash (P〈0.025) and combustible matter (P〈0.025). In a mildly uremic group there were similar trends in mean values but the only significant difference was an increase (P〈0.001) in trabecular bone water.
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    Effect of salmon calcitonin infusion on plasma concentrations of recently administered45Ca (1977)
    Springer
    Calcified tissue international 24 (1977), S. 201-208 
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    ISSN: 1432-0827
    Keywords: Calcitonin ; Plasma calcium ; Radiocalcium ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effect of intravenous salmon calcitonin (SCT) infusion on the net rate of loss from plasma of recently injected45Ca has been studied in conscious fasted rats, some of which had been previously thyroparathyroidectomized (TPTX). The45Ca was injected 10 h prior to or 1 or 2 h after the initiation of the infusion. Salmon calcitonin (0.05–0.2 MRC mU/g body weight/h) infusion produced the expected hypocalcemia and hypophosphatemia. The drop in plasma calcium levels produced by the hormone was lowered further by the addition of phosphate to the infusate. Plasma45Ca changes, during SCT infusion, followed a biphasic pattern when the radionuclide injection preceded SCT infusion by 10 h. During the first part of the infusion, the rate of loss of45Ca from plasma was greater in SCT-treated than in control rats. Later, this pattern reversed, and the rate of loss of45Ca from plasma became slower in SCT-treated animals. If45Ca was injected after SCT infusion was initiated only the second phase of the biphasic effect was observed; i.e., disappearance of45Ca from plasma was slower in SCT-infused than in control rats. These data are considered to support the hypothesis that rapid and opposing calcium fluxes exist between bone fluid and plasma, and that calcitonin acts by decreasing the calcium efflux from bone fluid. The calcium moved in this efflux system includes some that has only recently entered bone fluid from plasma. This is the explanation given for the initial decrease in plasma45Ca concentrations following SCT infusion. The reverse effect in the second phase can be explained as the result of a secondary reduction in calcium influx to bone fluid from plasma.
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    An X-ray study of the paracrystalline nature of bone apatite (1977)
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    Calcified tissue international 24 (1977), S. 243-248 
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    ISSN: 1432-0827
    Keywords: Paracrystallinity ; Hydroxyapatite ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary X-ray diffraction patterns from oriented bone sections show that the crystalline apatite content of untreated mature cortical bovine bone has, in fact, a paracrystalline structure (i.e., no long range order). There is anisotropy in both lattice distortions and the sizes of the coherently diffracting domains. The paracrystalline mean distance fluctuations, (g) were found to be 1.5 (±0.1)% and 2.9 (±0.2)% for the basal and prism planes respectively, the corresponding paracrystalline sizes being 220 (±20) and 70 (±10) Å. The paracrystalline structure became more ordered above 600°C, suggesting the association of hydroxyl and possibly carbonate and other ions with the paracrystalline structure. The paracrystalline model for bone apatite helps explain anomalies between X-ray and electron microscope measurements of crystal size and also some of the biological functions of the crystalline apatite.
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    Plasma proteins present in human cortical bone: Enrichment of theαHS-glycoprotein (1977)
    Springer
    Calcified tissue international 22 (1977), S. 27-33 
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    ISSN: 1432-0827
    Keywords: Protein ; Bone ; Blood plasma ; Dentine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The spectrum of plasma proteins present in human cortical bone and permanent dentine has been determined. One plasma glycoprotein, theαHS-glycoprotein, was found to be present at a high concentration in both bone and dentine and was shown to be concentrated in the mineralized tissues with respect to the other plasma proteins by factors of between 30 and 100. In this respect theαHS-glycoprotein is analogous to the G2B-glycoprotein and α-glycoprotein of bovine and rabbit b one, respectively. The binding ofαHS-glycoprotein and albumin to calcium phosphates generated within serum samples has been studied at different serum: precipitate ratios. In each case all theαHS-glycoprotein was removed from the samples and theαHS-glycoprotein was concentrated with respect to albumin by factors ranging from 370 at the highest serum: precipitate ratio to 25 at the lowest ratio. The plasmaαHS-glycoprotein concentrations of patients with Paget's disease of bone were shown to be substantially lower than the normal range, with significant negative correlation between theαHS-glycoprotein concentration and the plasma alkaline phosphatase activity.
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    Bone water (1977)
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    Calcified tissue international 23 (1977), S. 1-5 
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    ISSN: 1432-0827
    Keywords: Water ; Bone ; Homeostasis ; Structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A short review is given of the water in bone. Various analyses of bone water content are discussed, and its possible location is considered in relation to the behaviour of water in isolated components of bone. Some of the difficulties encountered in examining such microscopic phenomena as water structure in a heterogeneous system such as bone are also discussed.
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    Ethane-1-hydroxy-1,1-diphosphonate (EHDP) effects on incorporation and accumulation of osteoclast nuclei (1977)
    Springer
    Calcified tissue international 22 (1977), S. 243-252 
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    ISSN: 1432-0827
    Keywords: Diphosphonate ; Bone ; Osteoclasts ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Male rats weighing 100 g were injected with vehicle (control group), 0.4 or 4.0 mg/kg/day of ethane-1-hydroxy-1,1-diphosphonate (EHDP). Beginning after 6 days of EHDP treatment all rats received six subcutaneous injections of3H-thymidine at 8 h intervals. The multiple labeling index of autoradiographically defined labeled cells was determined for the osteoprogenitor cells of the primary spongiosa of the proximal tibial metaphysis. The osteoclasts in the proximal tibial metaphysis were assayed for population parameters and incorporation of labeled nuclei at sequential intervals after the administration of3H-thymidine. After 6 days of EHDP pre-treatment the multiple labeling index of the osteoprogenitor cells was reduced with 4.0 mg/kg/day dose of EHDP. At the beginning of the experimental kinetic sampling period, after the 6 days of EHDP pre-treatment, EHDP treatment resulted in significant increases in the numbers of osteoclasts, nuclei per osteoclast profile, and total osteoclast nuclei. During the sampling period, the 4.0 mg/kg/day dose of EHDP caused further increases in the number of total osteoclasts. EHDP treatment caused a marked increase in the rate of incorporation and accumulation of3H-thymidine-labeled nuclei in osteoclasts. Thus, EHDP causes an accelerated rate of osteoclast production from precursor cells in spite of its ability to slow bone resorption. Although the origin of osteoclast nuclei is not clear, the kinetic data from this study suggests that osteoclast nuclei are not arising from osteoprogenitor cells or osteocytes in the EHDP-treated animals.
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    Comparison of effects of parathyroidectomy and ethane-1-hydroxy-1,1-diphosphonate (EHDP) administration upon bone synthesis of hydroxyproline and urinary excretion of hydroxyproline in rats (1977)
    Springer
    Calcified tissue international 23 (1977), S. 115-119 
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    ISSN: 1432-0827
    Keywords: Parathyroidectomy ; Diphosphonates ; Bone ; Collagen ; Hydroxyproline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) may impair mineralization and reduce turnover of bone. However, its administration has been shown to lead to an accumulation of osteoid in both man and the rat. Using rats, the effects of surgical parathyroidectomy and administration of EHDP (30 mg EHDP/kg body weight by subcutaneous injection daily for 5 days) upon bone composition, uptake of3H-proline into hydroxyproline in bone and the subsequent urinary excretion of labelled and unlabelled hydroxyproline have been compared. Both parathyroidectomized (PTX) rats and EHDP-treated animals accumulated more hydroxyproline in bone and excreted less total urinary hydroxyproline than sham-PTX control animals, the changes induced by EHDP being of greater magnitude than those induced by surgical parathyroidectomy. Skeletal buildup of hydroxyproline was associated with decreased catabolism of mature collagen rather than enhanced synthesis of hydroxyproline in bone. EHDP administration, although decreasing urinary excretion of newly synthesised hydroxyproline, did not alter the skeletal synthesis of hydroxyproline as measured by uptake of3H-proline. In all parameters measured, responses to EHDP were similar in PTX and sham-PTX rats. It is concluded that depression of parathyroid hormone mediated bone turnover may have contributed to, but did not fully account for, the lowering of bone turnover and changes in bone composition induced by EHDP in sham-PTX rats in the present experiment.
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    The ultrastructure of the extracellular phase of bone as observed in frozen thin sections (1977)
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    Calcified tissue international 23 (1977), S. 215-223 
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    ISSN: 1432-0827
    Keywords: Amorphous mineral ; Bone ; Electron microscopy ; Ultracryotomy ; Ultramicro-incineration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The fine structure of the extracellular phase of avian medullary bone and embryonic chick femur was examined in thin sections prepared by ultracryotomy and ultramicroincineration. Since contact with solutions was completely avoided, little or no loss or dislocation of mineral constituents could occur. Amorphous bone mineral (ABM) was present in two forms: as 15–30 nm spheres and as a structure-free haze. Removal of all organic material by low temperature ashing left the ABM intact. Crystals were usually associated with the ABM. In newly ossifying regions clusters or nodules of randomly oriented crystals and ABM appeared to coalesce when they reached approximately 1 μm in diameter. In highly calcified regions crystals appeared to be oriented along collagen fibers. ABM did not appear to be associated with collagen. Unmineralized collagen was visible in osteoid after staining with dry OsO4 vapor and it appeared to be diverted around nodules. Structures which resembled matrix vesicles were present. Selected area electron diffraction patterns indicated the presence of hydroxyapatite.
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    Movement of125I albumin and125I polyvinylpyrrolidone through bone tissue fluid (1977)
    Springer
    Calcified tissue international 23 (1977), S. 103-112 
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    ISSN: 1432-0827
    Keywords: Albumin ; Polyvinylpyrrolidone ; Tissue fluid ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The passage of tissue fluid through cortical bone has been investigated using radioactively labelled macromolecules as markers. The results suggest that in the cortex of young rabbit femur the movement of tissue fluid is in the same net direction as blood, mainly from the endosteal to the periosteal surface. Some albumin is incorporated from extravascular tissue fluid into calcified matrix at sites of bone formation. Polyvinylpyrrolidone, average molecular weight 35,000 is able to pass through extravascular tissue fluid in bone but isnot incorporated into calcified matrix. In rabbits made vitamin D deficient, much less albumin is retained in regions of bone formation than is the case with controls. Albumin adsorbs to the surface of calcium phosphate precipitates and it is suggested that this mechanism may be mainly responsible for its incorporation into bone.
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    Absorption spectra of bone (1977)
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    Calcified tissue international 23 (1977), S. 113-114 
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    ISSN: 1432-0827
    Keywords: Bone ; Absorption Spectra ; Collagen ; Hydroxyapatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Absorption spectra of human bone and its two major constituents (collagen and apatite) were obtained in the wavelength region extending from 2000 to 12,000 Å. In the last two cases a, minimum transmission (maximum absorption) was uniformly observed in the ultraviolet region. The two samples after exposure to ultraviolet radiations show a shift in the peak positions. Absorption peaks in the total bone spectra are not reproducible in its two constituents. After exposure to UV radiations the position of maximum absorption is displaced. A possible interpretation of the observed results is presented.
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    Mechanism of induction of hypercalcemia and hyperphosphatemia by lead acetate in the rat (1977)
    Springer
    Calcified tissue international 24 (1977), S. 41-46 
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    ISSN: 1432-0827
    Keywords: Lead salt ; Bone ; Mobilization ; Hypercalcemia ; Hyperphosphatemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The present study is an investigation of the mechanism of hypercalcemia and hyperphosphatemia induced by the intravenous injection of lead acetate (Pb-Ac). A total of 118 male rats were injected with 30 mg/kg of Pb-Ac, or with 16.5 mg/kg of sodium acetate as the control. The levels of serum calcium, phosphorus and lead were then determined at various time periods after the injections. Serum calcium and phosphorus levels increased with time after Pb-Ac injection and the maximum values of calcium (17 mg%) were found after 1 h and of phosphorus (13.5 mg%) after 30 min. Both calcium and phosphorus levels reverted to the normal range after 12 h. The maximum net rates of increase of calcium and phosphorus were found immediately after Pb-Ac injection. At that time, deposition of lead at the calcifying sites of bone and incisor dentin was demonstrated by a histochemical examination. In other experiments the changes in the calcium and phosphorus contents in the medium after shaking bone powder in serum with Pb-Ac in an in vitro system were studied. It was confirmed that the calcium and phosphorus were displaced from the bone mineral, the extent of the displacement being correlated with the concentration of the Pb-Ac added to the medium, and that these displacements were very rapid reactions. These results suggest that hypercalcemia and hyperphosphatemia following Pb-Ac injection results from a direct action of lead on the bone mineral.
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    Ultrahistochemical analysis of glycosaminoglycan hydrolysis in the rat periodontal ligament (1977)
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    Calcified tissue international 24 (1977), S. 143-149 
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    ISSN: 1432-0827
    Keywords: Bone ; Periodontal ligament ; Bone resorption ; Aryl sulfatase ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The distribution of aryl sulfatase in the rat periodontal ligament was investigated by ultrastructural histochemistry. In the periodontal ligament aryl sulfatase was localized specifically in osteoclasts and in vicinal perivascular macrophages. Macrophages associated with bone formation did not stain. The authors interpret this specificity as a potential marker for osteoclast differentiation from macrophages — or as a further indication of the capacity of macrophages to modulate their enzymatic complement in response to the environment. To explain the absence of aryl sulfatase in areas of bone formation we suggest that different sulfate esters are mobilized from resorbing and mineralizing matrices, and that only the enzyme associated with bone resorption is histochemically detectable with the artificial substrates currently used.
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    An interpretation of acute changes in plasma45Ca following parathyroid hormone administration to thyroparathyroidectomized rats (1977)
    Springer
    Calcified tissue international 22 (1977), S. 117-128 
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    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Plasma calcium ; Radiocalcium ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Acute changes in plasma calcium and45Ca were studied in young adult male thyroparathyroidectomized (TPTX) rats injected with moderate doses of parathyroid hormone (PTH). For plasma calcium changes, comparison was made between rats fasted or fed prior to PTH injection. For plasma45Ca changes, the effect of the time of administration of the radionuclide was also studied; this included rats injected with PTH 1 h after radionuclide (“1 h45Ca”), 18 h later (“18 h45Ca”) and more than 6 days later (“6 day45Ca”). The results can be summarized as follows: (1) Plasma calcium changes were greater when PTH was injected into “fed” rather than into “fasted” rats. (2) PTH always produced a relative increase (compared to controls tested concurrently) in plasma45Ca concentrations. This increase was the same in the “1 h45Ca” and the “18 h45Ca” groups. (3) Plasma45Ca rose at least temporarily following PTH injection in the “18 h45Ca” group. (4) The45Ca rise following PTH was always greater in “fed” than in “fasted” groups. (5) Plasma45Ca specific activities (S.A.) tended to rise in the “6 day45Ca” group and to fall in the “18 h45Ca” group, following PTH injection. However, the45Ca S.A. was always higher in fed than fasted groups. (6) In a few experiments in which32P was injected with45Ca, specific activity changes in plasma45Ca following PTH injection werenot accompanied by similar changes in32P specific activity. These results could not be adequately explained by PTH effects on bone resorption, but the data supported the postulate that PTH controls plasma calcium concentrations by increasing transport of calcium through the osteocyte-lining cell (osteoblast) bone cell complex from the bone fluid compartment to the ECF.
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    A new tracer method for the calculation of rates of bone formation and breakdown in osteoporosis and other generalised skeletal disorders (1977)
    Springer
    Calcified tissue international 22 (1977), S. 191-206 
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    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Strontium ; Apposition ; Tracer analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract 1. Evidence has accumulated that the rate of acceretion (A) of calcium to bone is the sum of two fluxes; apposition involving the laying down of new bone and augmentation which is the result of slow exchange of non-surface bone calcium with plasma calcium pools as the result of solid state diffusion. 2. A method has been devised for separating A into its two components. It requires the use of45Ca or, for clinical studies,85Sr as a calcium tracer. Studies which are initiated with a combined accretion rate-calcium balance study, are concluded with an estimate of the exponent of the power function which has been found to describe the whole body retention of tracer from the second month onward. 3. The impulse response function of the skeleton for the tracer is then calculated, making the assumption that in any uniform volume of bone, osteoclastic resorption is a first order process. Making in addition certain simplifying assumptions, which are shown to have a modest influence on the final results, a mean rate of bone resorption can be calculated using a development of the well known Stewart-Hamilton formula. The apposition rate is calculated as the sum of the resorption rate and the calcium balance. Augmentation and diminution, defined as equal and opposite exchange processes, are given by the difference between A and the apposition rate. 4. The results of our first thirteen studies in normal subjects and patients with metabolic bone disease are presented, together with analyses of some data from the literature. It is concluded that the development of an atraumatic method for measuring rates of bone formation and resorption in the whole body would be an important advance in the study of metabolic bone disease, and this work is presented so that critical comparisons may be initiated between this tracer method and independent histological methods for measuring these parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010358
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    Magnesium and the mineral metabolism of chick embryo tibiae in organ culture (1977)
    Springer
    Calcified tissue international 24 (1977), S. 93-98 
    Details
    ISSN: 1432-0827
    Keywords: Magnesium ; Bone ; Mineral ; Chick embryo ; Organ culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Using bone organ culture techniques, three concentrations of magnesium were evaluated for their effects on the mineral mass of embryonic chick tibiae incubated for 3 days with or without a metabolic inhibitor (1 mM iodoacetic acid) added to the media. Varying the medium Mg level from 0.3 to 3.0 mM had little effect on the net increase in mineral in live bones (without the inhibitor), but in dead tibiae (with the inhibitor) there was a marked net decrease in mineral deposition with increasing Mg concentration. Bone Mg mass varied directly with the level of Mg in the medium regardless of whether or not the tibiae were inhibited. Responsiveness to parathyroid hormone (PTH) with regard to mineral loss and increased lactate production was not affected by Mg even in tibiae incubated in Mg-free media. However, PTH-treated bones cultured in Mg-free media had a significantly elevated Mg mass, suggesting that the hormone may have a Mg-conserving effect on bone during severe Mg deficiency. The findings of this study support the hypothesis that bone cells regulate the level of Mg to which newly forming mineral is exposed and that PTH-responsiveness in embryonic chick tibiae is not dependent on the ambient Mg concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02223301
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    The comparative effects of dichloromethylene diphosphonate (Cl2MDP) and ethane-1-hydroxy-1,1-diphosphonate (EHDP) on growth and modeling of the rat tibia (1977)
    Springer
    Calcified tissue international 23 (1977), S. 207-214 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Diphosphonates ; Bone resorption ; Bone formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Male rats weighing 100 g were assigned to groups and injected daily for 10 days with vehicle (control), 0.4, 2.0, 4.0, 10.0, or 20.0 mg/kg/day of ethane-1-hydroxy-1,1-diphosphonate (EHDP) or dichloromethylene diphosphonate (Cl2MDP). The proximal tibial metaphysis and epiphysis were assayed for changes in percentage of hard tissue and bone formation parameters. From the data, information about hard tissue resorption was deduced. All doses of Cl2MDP and doses of 2.0 mg EHDP/kg/day and greater caused significant increases in percentage of hard tissues with Cl2MDP being more effective than similar doses of EHDP in decreasing bone resorption. Osteoclast population parameters were increased with all doses of both Cl2MDP and EHDP with Cl2MDP having a greater effect than similar doses of EHDP. Decreases in the proliferation of the osteoprogenitor pool parallel the decreases in osteoblasts and bone formation parameters. These decreases in osteoprogenitor pool proliferation do not account for the increases with diphosphonates in osteoclast population parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02012787
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    Effect of endogenous and infused parathyroid hormone on plasma concentrations of recently administered45Ca (1977)
    Springer
    Calcified tissue international 24 (1977), S. 209-214 
    Details
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Plasma calcium ; Radiocalcium ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The net rate of loss of45Ca from plasma was monitored in normal, thyroparathyroidectomized (TPTX), and nephrectomized rats. Also studied was the effect of a 24 h intravenous infusion of PTH in TPTX rats. The45Ca was injected after an overnight fast and 1 to 4 h prior to the time the first blood sample was obtained. In normal rats, the net rate of loss of45Ca from plasma was slower than in TPTX rats for at least 12 h after radionuclide injection. Nephrectomy did not affect this difference between control and TPTX rats until 8 h after45Ca injection or about 18 h after nephrectomy. At this time a reversal occurred and the net rate of plasma45Ca loss in nephrectomized rats with parathyroids became faster than in TPTX nephrectomized rats. When PTH was infused at a constant rate (3 mU/g body weight/h) plasma calcium concentrations rose gradually for approximately 12 h after which a constant plasma calcium level was maintained with continued PTH infusion. During the period when plasma calcium concentrations were rising, the net rate of loss of45Ca from plasma was slower than in TPTX controls infused only with saline. However, when plasma levels stabilized, plasma45Ca disappearance rates changed such that the rate loss of45Ca from plasma became faster in PTH-infused than in TPTX controls. It is concluded that PTH increases calcium efflux from the same compartment in bone which receives calcium from plasma, thereby returning some recently deposited45Ca to plasma. In the non-equilibrated state, this returns additional45Ca to plasma causing anet decrease in the rate of loss of45Ca from plasma. However, in the equilibrated condition, when both calcium efflux from bone and influx into bone are in balance but at higher flux rates, PTH stimulates the diffusion of45Ca into other bone compartments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02223318
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    Quantitative analyses of osteoclast changes in resorbing bone organ cultures (1977)
    Springer
    Calcified tissue international 23 (1977), S. 283-289 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Resorption ; Osteoclast ; Quantitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The stimulation of bone resorption, assessed by the release of45Ca from prelabeled bones, was associated with an increase in number of osteoclasts per bone section in parathyroid hormone (PTH)-treated bones, but not in lipopolysaccharide (LPS)-treated bones. By contrast the number of nuclei per osteoclast increased following LPS treatment, but was not affected by PTH. LPS-treated bones had more multinucleated cells, some having as many as 27 nuclei per osteoclast. More osteoclasts were adjacent to the bone collar in bones treated with LPS or PTH than in control bones. In LPS-treated bones this area also contained the largest osteoclasts, as determined by the greatest number of nuclei per osteoclast. The results suggest that LPS and PTH stimulate osteoclastic resorption by different mechanisms.
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    URL: http://dx.doi.org/10.1007/BF02012798
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    Relations between tensile impact properties and microstructure of compact bone (1977)
    Springer
    Calcified tissue international 24 (1977), S. 65-72 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Strength ; Tension ; Microstructure ; Osteon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Standardized human and beef femoral compact bone specimens were tested in tensile impact and the dynamic mechanical properties were determined. The microstructure of 45 beef and 47 human bone specimens were examined histologically to determine if there is a structural basis to account for strength differences in the bone samples. Strong negative correlations were obtained between the maximum stress and the percentage area of secondary osteons in each specimen. For human bone samples, the energy absorption capacity and the modulus of elasticity were also found to have strong negative correlations with the percentage area of secondary osteons present in each specimen. Linear regression equations were obtained describing the impact strength properties in terms of the percentage areas of secondary osteons and cavities in the samples. Fracture surfaces of the tested bone specimens were examined in a scanning electron microscope. Most surfaces exhibited a fairly rough texture indicating a quasi-cleavage type of failure. Fractographic analysis of bone fracture surface was helpful in understanding the micromechanics of bone fracture.
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    URL: http://dx.doi.org/10.1007/BF02223298
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    Elastic and strength properties of canine long bones (1977)
    Springer
    Medical & biological engineering & computing 15 (1977), S. 72-74 
    Details
    ISSN: 1741-0444
    Keywords: Bone ; Elasticity ; Mechanical strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The mechanical properties of canine long bones have been determined. The mean and standard deviation of the maximum load supported by six fresh canine femurs in 3-point bending was 1366±253 N. In all cases, the bones sustained a considerable amount of plastic deformation before failure. The modulus of elasticity (GN/m2), ultimate tensile stress (MN/m2) and yield stress (MN/m2) were 13·86, 108·3 and 88·3 for six humeral specimens and 13·88, 142·1 and 104·0 for 13 tibial specimens, respectively. The tibial specimens showed a statistically significant higher ultimate strength than the humeral specimens.
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    URL: http://dx.doi.org/10.1007/BF02441578
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    Some morphological observations on osteoclasts (1977)
    Springer
    Cell & tissue research 185 (1977), S. 387-397 
    Details
    ISSN: 1432-0878
    Keywords: Osteoclasts ; Resorption ; Bone ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Osteoclasts of the peripheral portions of the endocranial aspect of young rat parietal and frontal bones were studied by scanning electron microscopy of glutaraldehyde fixed, critical point dried specimens. These studies show Osteoclasts to have a much more complicated form than has previously been realised. Extensively branching, elongated, smooth-surfaced cells, which are for the most part elevated above the level of the surrounding bone matrix surface and sometimes above portions of osteoblasts or other osteoclasts, were identified as motile non-resorbing cells. Portions of the former and other entire cells may be embowered in Howship's lacunae, have microvilli on their dorsal surface, and are surrounded by a serrated border of microprojections which have an apparently firm attachment to the matrix surface. Osteoclasts in short term culture show additional free surface ruffles which are not encountered in specimens taken fresh from the animal. No evidence of recruitment of osteoblasts or osteocytes into osteoclasts was found. Disinterred osteocytes retained an ability to migrate from their lacunae on to surrounding bone matrix surface.
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    URL: http://dx.doi.org/10.1007/BF00220298
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    Instrumentation for measuring the tensile properties of femoral cortical bone (1977)
    Springer
    Medical & biological engineering & computing 15 (1977), S. 207-208 
    Details
    ISSN: 1741-0444
    Keywords: Bone ; Instrumentation ; Tensile strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02442967
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    Effect of calcium depletion and subsequent repletion on parathyroids, parafollicular (C) cells and bone in the growing pig (1976)
    Springer
    Cell & tissue research 168 (1976), S. 373-384 
    Details
    ISSN: 1432-0878
    Keywords: Calcium ; Bone ; Parathyroid ; Parafollicular cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the chief cells of the parathyroid gland and thyroid parafollicular (C) cells and the morphology of bone in calcium depletion and subsequent repletion were examined in young growing pigs. A low calcium diet resulted in osteopenia, increased removal of the cartilaginous core, osteoclasia and osteocytic osteolysis. Subsequent repletion quickly returned bone to normal. In pigs fed the low calcium diet, there was a marked depletion of secretory granules but a striking increase in the number of microtubules in chief cells. Increasing the calcium content of the diet to normal quickly returned the ultrastructural appearance of chief cells to apparent normal. In the initial response to calcium repletion, chief cells exhibited large number of lysosomes and occasionally prominent paracrystalloid bodies. Electron microscopic examination of parafollicular (C) cells of the thyroid gland failed to reveal differences in ultrastructure between test and control pigs. These findings support the view that bone resorption following calcium deficiency may be the result of a secondary hyperparathyroidism rather than of calcium deficiency per se.
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    URL: http://dx.doi.org/10.1007/BF00215314
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    Scanning electron microscopy of bone cells in culture (1976)
    Springer
    Cell & tissue research 166 (1976), S. 65-70 
    Details
    ISSN: 1432-0878
    Keywords: Collagen ; Bone ; Cell culture ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Embryonic and young rat bone cells have been grown in culture and examined in the scanning electron microscope (SEM). Compared with cells fixed in situ and taken directly from the animal, the cultured osteoblastic cells were smoother, flatter and more extensive and showed tighter intercellular contacts. Some matrix is formed in culture and undergoes at least partial mineralization as judged by the accumulation of Ca and P measured by energy dispersive x-ray analysis. Findings concerning the morphology of the collagen arrangement were indecisive. Some superficial cells, free of surrounding matrix, resembled osteocytes in normal in vivo bone. This may indicate that a proportion of the extracellular matrix produced by the cultured cells failed to polymerise into recognizable bone matrix, and that osteocytic morphology is not dependent upon the physical characteristics of the bone matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215125
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    Experimental study of changes in osteoblastic shape induced by calcitonin and parathyroid extract in an organ culture system (1976)
    Springer
    Cell & tissue research 169 (1976), S. 449-465 
    Details
    ISSN: 1432-0878
    Keywords: Bone ; Osteoblasts ; Cell surface ; Cell shape ; Calcitonin ; Parathyroid extract ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neonate rat endocranial osteoblasts were cultured on their bone surfaces in control medium (CC) or medium to which either parathyroid extract (PTE) or calcitonin (CT) had been added for 2, 4, 8 or 24 h. Some were cultured for 24 h in CC, then for 2, 4, 8 or 24 h in either CT or PTE medium; or for 24 h in PTE, then for 2, 4, 8 or 24 h in either CC or CT; or 24 h in CT and 2, 4, 8 or 24 h in CC. The dorsal ruffling of the cells in CC was found to be suppressed by later culturing with PTE and the disoriented cells reorganized to form arrays of parallel cells. The effects of PTE were also reversed by CC or CT: the osteoblasts in the second culture (CC) lost elongation and order, and proceeded through a proliferative phase before exhibiting the ruffling form similar to a single CC 24 h culture. PTE-cultured osteoblasts showed an increase in cell overlap and contact so that a more competent barrier was formed separating the bone from the medium. In control or CT medium, however, intercellular gaps were greater than in vivo.
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    URL: http://dx.doi.org/10.1007/BF00218146
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