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  • Calcium  (7)
  • Bone
  • hypertension
  • oxidation
  • Springer  (15)
  • Annual Reviews
  • Oxford University Press
  • 1980-1984  (15)
  • 1975-1979
  • 1980  (15)
Collection
Keywords
Publisher
  • Springer  (15)
  • Annual Reviews
  • Oxford University Press
Years
  • 1980-1984  (15)
  • 1975-1979
Year
  • 1
    Electronic Resource
    Electronic Resource
    Rhythmic dentinogenesis in the rabbit incisor: Allometric aspects (1980)
    Springer
    Calcified tissue international 32 (1980), S. 45-53 
    Details
    ISSN: 1432-0827
    Keywords: Dentin ; Periodicity ; Allometry ; Calcium ; Sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have described differences in the aspects of biological rhythms for calcium and sulfur deposition on the labial and lingual sides of the growing rabbit incisor, where growth occurs along a spiral axis. The calcium oscillations appear to be smoother on the labial side than on the lingual side. The lingual side is characterized by high-frequency rhythms with high amplitudes which possess the greatest percent of the power (Fourier analysis). These observations also reflect a difference in behavior of the mean Ca concentration across the labial and lingual sides. Sulfur rhythms on the labial side have higher amplitudes than those on the lingual side, but systematic differences in distribution of power between high and low frequencies is not as pronounced as in the case of Ca. The differences in Ca rhythms reflect differences in the growth rates of incisors on either side of the spiral axis. The labial side grows slightly faster than the lingual side, and its odontoblasts secrete Ca along the spiral axis and toward the pulp cavity at the same time. Thus the resultant direction of growth is more nearly opposite the extension of the occlusal end on the labial side, and Ca is consequently deposited over a wider area relative to that on the lingual surfaces. On the lingual side, Ca is deposited within a more limited area, and growth must therefore be continuous at high frequencies. The distribution of Ca on both sides of the tooth reflects these differences in growth rate and periodicity in two ways. First, given a unit area of tooth, the calcium concentration on the labial side is less than that of the lingual side. Second, whereas the calcium concentration on the labial side declines rapidly from the enamel-dentin junction to the pulp cavity, it is uniformly high across the lingual side because its growth is more continuous at high frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408520
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  • 2
    Electronic Resource
    Electronic Resource
    Rhythmic dentinogenesis in the rabbit incisor: Circadian, ultradian, and infradian periods (1980)
    Springer
    Calcified tissue international 32 (1980), S. 29-44 
    Details
    ISSN: 1432-0827
    Keywords: Rabbit ; Dentin ; Calcium ; Sulfur ; Periodicity ; Circadian ; Ultradian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have identified a variety of biological rhythms involved in the apposition and mineralization of dentin in the rabbit incisor. Animals were injected during the day or night with lead acetate at 2-week intervals—to provide biological time markers in forming dentin—and transverse undecalcified sections of the lower incisors were prepared for electron microprobe analysis. The positions of the lead markers were identified, and the continuous distribution of calcium and sulfur was measured at 1 µm intervals between the markers. In thin sections stained with hematoxylin after decalcification, the widths of a series of structural increments (bands) were measured with an ocular micrometer. Fourier analysis of the data revealed spectra of structural and compositional rhythms with a range of periodicities which extended from a matter of hours [ultradian (〈24 h)] to days [infradian (〉24 h) and circadian (approximately 24 h)]. The structural and compositional rhythms appeared to be independent to the extent that they did not necessarily have the same periods, or amplitudes. Nor were there simple phase relationships between all of the rhythms. At some times, Ca and S fluctuations are inversely proportional (180° out of phase), but in other cases they are directly proportional or out of phase by varying degrees other than 180°. The analyses thus suggest that calcium and sulfur deposition (representing mineral and glycosaminoglycan deposition, respectively) are not simply inversely proportional, and that the hematoxylin-stained structural increments did not solely reflect differences in the distribution of the mineral components in dentin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408519
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  • 3
    Electronic Resource
    Electronic Resource
    The oxidation of Ni-70 wt.%Cr in oxygen between 1073 and 1473°K (1980)
    Springer
    Oxidation of metals 14 (1980), S. 263-277 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; Ni-Cr alloys ; two-phase alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation of the relatively simple, two-phase alloy Ni-70 wt.%Cr in oxygen between 1073 and 1473°K results in the formation of a Cr2O3 scale containing less than O.5 wt.% Ni in solid solution. The oxidation kinetics are irreproducible for an initial period, which is brief at 1073 and 1273°K but much more pronounced at 1473°K, both in duration and degree. This behavior is associated with the failure of the protective Cr2O3 scale. However, after longer periods a compact layer of Cr2O3 becomes established under isothermal conditions and results in a change to more reproducible kinetics, especially at 1073 and 1273°K. Oxidation causes chromium depletion and the formation of a single-phase zone which separates the scale and the two-phase bulk alloy. The depth of Cr2O3 internal oxide coincides with this zone. The oxidation behavior is compared with that of more Ni-rich, single-phase Ni-Cr alloys, with particular reference to the effects of the constitution of the underlying alloy and the integrity of the protective oxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00604568
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  • 4
    Electronic Resource
    Electronic Resource
    Human vertebral bone: Relation of strength, porosity, and mineralization to fluoride content (1980)
    Springer
    Calcified tissue international 32 (1980), S. 189-194 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Fluoride ; Strength ; Porosity ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Radiographically normal vertebral bone cylinders from 80 male subjects were tested mechanically by static compression and analyzed for porosity, fluoride and ash content. As a group, they had low fluoride content, suggesting little prior intake, consonent with this geographic area. Nevertheless, increasing levels of fluoride were associated with bulkier bone, less porosity, and less mineral per unit of bone, which in direction though not degree suggested changes similar to those of osteomalacia and opposite from those of osteoporosis without apparent threshold. The higher fluoride hard tissue was weaker in static tests than that with less fluoride, but the increased bulk apparently offset this, resulting in bones of unchanged static strength. Hence, water fluoridation should not alter static bone strength. There has, however, been a recent report suggesting that increased mineralization of bone renders it more brittle and thus more likely to fracture on impact. Therefore, the possibility that fluoridation may increase impact resistance by lessening mineralization can be entertained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408540
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of a bone resorptive factor from human cancer ascites fluid on rat bone cell calcium and cyclic AMP (1980)
    Springer
    Calcified tissue international 30 (1980), S. 191-197 
    Details
    ISSN: 1432-0827
    Keywords: Bone cells ; Cyclic AMP ; Calcium ; Ascites fluid resorptive protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of a bone resorptive protein isolated from human cancer ascites fluid on bone cell calcium and cyclic AMP were studied with fetal rat cells. The osteoclast-activating factor increased bone cell calcium uptake at 37°C and 4°C with no direct effects on calcium efflux. Concentrations of the resorptive factor that increased in vitro bone resorption and cell calcium uptake had no effect on cyclic AMP. The effects of the protein on calcium uptake were not specific for bone cells, and large increases were also observed in isolated fetal rat skin cells. These studies suggest that increases in the permeability of the cell membrane to calcium are involved in the mechanism of action of the ascites fluid resorptive protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408627
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  • 6
    Electronic Resource
    Electronic Resource
    Uptake and loss of plutonium from osteoclasts and macrophages in the mandibular condyle of the rat (1980)
    Springer
    Calcified tissue international 30 (1980), S. 15-20 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Osteoclasts ; Macrophage ; Resorption ; Plutonium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Female rats were used to study the kinetics of plutonium transfer from the bone surfaces of the mandibular condyle to osteoclasts and macrophages. This study was made using autoradiographs prepared from plastic sections of the mineralized bones of animals which had been injected with241 Pu citrate. Measurements of the concentration of plutonium in the osteoclasts and macrophages at different times after the injection of plutonium showed that plutonium was concentrated by osteoclasts from bone surfaces and was retained with a half-time of ∼ 70 h. Subsequently, plutonium appeared to be transferred to macrophages. The results showed that plutonium was unlikely to be accumulated by macrophages as a result of their participation in bone resorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408601
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of pyrophosphate and diphosphonates on the dissolution of hydroxyapatites using a flow system (1980)
    Springer
    Calcified tissue international 31 (1980), S. 153-159 
    Details
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Dissolution ; Pyrophosphate, Diphosphonates ; Calcium ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Pyrophosphate and diphosphonate ions have been said to diminish the dissolution of hydroxyapatite crystals, because they lower the equilibrium concentrations of calcium and phosphate ions in the bulk solution around hydroxyapatite crystals in a closed system. However, in a closed system these effects are not necessarily due to an effect on dissolution alone. In this paper we have used a continuous flow system to study the effects of pyrophosphate and two diphosphonates, ethane-1-hydroxy-1,1-diphosphonate and dichloromethane diphosphonate, on the dissolution of hydroxyapatite. All three compounds decreased markedly the rate of dissolution of hydroxyapatite as well as the exchangeable pools of calcium and phosphate ions around the cystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02407176
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  • 8
    Electronic Resource
    Electronic Resource
    Histological observations on the failure of rachitic rat bones to respond to 1,25/OH)2D3 (1980)
    Springer
    Calcified tissue international 31 (1980), S. 215-223 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; 1,25(OH)2D3 ; 25OHD3 ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Rachitic rats, maintained on diets with low or normal P contents, were given daily intraperitoneal doses of 1,25(OH)2D3 or 25OHD3 at levels of 100 or 200 ng. Plasma chemistry was measured and the ash content and histological appearance of the bones investigated. Using labeled material it was shown that the dosing levels of 1,25(OH)2D3 employed ensured a higher than normal plasma concentration of that metabolite over the period between doses. 1,25(OH)2D3 was not as effective as 25OHD3 in raising bone ash or reducing the amount of osteoid. The difference between the effects of the metabolites was evident at both dietary P levels, but more marked at the higher P level. In contrast, the metabolites reduced the width of the epiphyseal plate to an approximately similar degree, and this is possibly the reason why there are discrepancies between previous reports of the effectiveness of 1,25(OH)2D3 compared with 25OHD3 or vitamin D3. Dosing with 1,25(OH)2D3 failed to maintain a constant plasma Pi value over the period between doses in animals fed the low P diet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02407184
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of 1α-hydroxy vitamin D3 on the rachitic chick intestine: A comparison to the effects of 1,25-dihydroxyvitamin D3 (1980)
    Springer
    Calcified tissue international 32 (1980), S. 9-17 
    Details
    ISSN: 1432-0827
    Keywords: 1α-Hydroxy vitamin D3 ; 1,25-Dihydroxyvitamin D3 ; Calcium ; Transport ; Intestine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The timed sequence of events following the oral administration of 1α-hydroxy vitamin D3 (1αOHD3) to rachitic chicks was compared to that following a comparable dose of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3). RNA polymerase activity was maximally increased 20% by 1αOHD3 within 1 to 2 h and returned to control values after 8 h. Alkaline phosphatase activity was stimulated by 4 h and was maximal (3- to 5-fold increase) at 24 h. Calcium binding protein (CaBP) was detected initially within epithelial cells at the proximal end of the villus (just above the crypt) 6 to 8 h after 1αOHD3 administration, in epithelial cells lining the proximal half of the villus by 24 h, and in epithelial cells along nearly the entire villus by 48 h. At no time did goblet cells contain CaBP. Serum calcium concentrations were significantly elevated in 2 h and maximal by 12 h (an increase of 3.6 mg/dl). Calcium accumulation by the intestinal mucosa in vitro was increased by 6 to 8 h and maximal (60% increase over controls) at 24 h. Phosphate accumulation by the intestinal mucosa in vitro was increased by 6 h and maximal (105% increase over controls) between 8 and 24 h. 1,25(OH)2D3 increased CaBP and calcium accumulation by 4 h, 2 h sooner than did 1αOHD3. 1,25(OH)2D3 decreased serum calcium levels and increased serum phosphate levels at 2 h unlike 1αOHD3. No difference in the effects of these compounds on alkaline phosphatase activity, RNA polymerase activity, and phosphate accumulation could be demonstrated. These results are consistent with the possibility that 1αOHD3 may not require conversion to 1,25(OH)2D3 for all of its biological effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408517
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of calcium in the mandibular condylar growth cartilage of the rat (1980)
    Springer
    Calcified tissue international 30 (1980), S. 27-34 
    Details
    ISSN: 1432-0827
    Keywords: Ultrastructure ; Calcium ; Cartilage ; Vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The potassium pyroantimonate technique was utilized for the selective subcellular localization of calcium in the mandibular condylar cartilage of 1-day-old rats. Electron dense calcium pyroantimonate precipitates were localized principally in mitochondria and at the cell membrane of the chondrocytes. In addition, small intracellular vesicles 0.1–0.2µm in diameter were observed in proximity to the cell membrane of chondrocytes of the mid-hypertrophic zone. The results suggest that these vesicles were being extruded from the cell into the extracellular matrix. Energy-dispersive analysis by X-rays confirmed that calcium is the principal cation of the electron-dense precipitates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408603
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