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  • Calcium  (11)
  • Springer  (11)
  • 1980-1984  (11)
  • 1982  (4)
  • 1980  (7)
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Keywords
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  • Springer  (11)
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  • 1980-1984  (11)
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
    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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  • 4
    Electronic Resource
    Electronic Resource
    On the role of calcium in chemotaxis and oscillations of dictyostelium cells (1982)
    Springer
    European biophysics journal 9 (1982), S. 131-136 
    Details
    ISSN: 1432-1017
    Keywords: Chemotaxis ; Calcium ; Oscillation ; Dictyostelium ; Ionophore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Migration of differentiated cells to a capillary containing cyclic AMP was enhanced in the presence of 1 mM CaCl2 and was virtually absent in the presence of 1 mM EGTA. Furthermore, the cells contracted and extended pseudopods to a capillary filled with the calcium ionophore A 23187. At short distances, migration to the tip of the capillary was observed. The ionophore also induced transient decreases of the optical density of suspended cells indicating changes of cell shape. These findings support the hypothesis that cyclic AMP-binding to cell surface receptors causes a local influx of calcium ions. These in turn lead to an increase of the cytosolic calcium concentration and subsequently to an activation of cell migration. Perturbing pulses of the ionophore induced permanent phase shifts of free-running light scattering oscillations. This result indicates that cytosolic calcium is an intrinsic component of the oscillatory system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00539112
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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
    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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  • 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
    Equilibrium dialysis and ultrafiltration studies of calcium and phosphate binding by human salivary proteins. Implications for salivary supersaturation with respect to calcium phosphate salts (1982)
    Springer
    Calcified tissue international 34 (1982), S. 531-538 
    Details
    ISSN: 1432-0827
    Keywords: Saliva ; Calcium ; Phosphate ; Ion-binding ; Supersaturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Previous ultrafiltration studies indicated that up to one-half of the calcium and two-thirds of the phosphate in human salivary secretions may be bound by salivary proteins. Since this binding is an important variable in determining the extent of salivary supersaturation with respect to calcium phosphate salts, and since the amount of binding reported is surprisingly large, calcium and phosphate ion-binding by salivary macromolecules has been reexamined. From experiments using equilibrium dialysis, it was found that (1) the fraction of salivary calcium involved in macromolecular complexes ranges from a few percent for unstimulated secretions, to no more than about 10% for stimulated glandular salivas, and (2) salivary proteins do not bind phosphate ions to any significant extent. These findings, and experiments using an improved ultrafiltration membrane, indicate that the earlier results were artifacts of the ultrafiltration technique. Fractionation of salivary proteins, followed by equilibrium dialysis measurements, showed that the anionic proline-rich proteins and a basic proline-rich glycoprotein are responsible for most of the calcium binding now observed. The finding that macromolecular complexes of salivary calcium and phosphate have been overestimated in the past, leads to the conclusion that salivary calcium and phosphate ion activities in stimulated salivary secretions may be up to 50 to 100% higher than previously thought. Revised values were therefore used to recalculate the degree of salivary supersaturation with respect to calcium phosphate salts. The results indicate that stimulated salivary secretions are supersaturated with respect to dicalcium phosphate dihydrate; this is a substantially greater degree of supersaturation than previously reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411299
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  • 9
    Electronic Resource
    Electronic Resource
    pH optima for crop growth (1980)
    Springer
    Plant and soil 54 (1980), S. 339-357 
    Details
    ISSN: 1573-5036
    Keywords: Calcium ; Cassava ; Chemical composition ; Control of solution pH ; Copper ; Flowing solution culture ; French bean ; Ginger ; Hydrogen ion injury ; Magnesium ; Maize ; Manganese ; Nitrogen ; Optimum pH range ; pH ; Plant growth ; Root weight ratio ; Tomato ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Ginger, cassava, maize, wheat, french bean and tomato were grown for periods up to six weeks in continuously flowing nutrient solutions at seven constant pH values ranging from 3.3 to 8.5. All species achieved maximum or near-maximum growth in the pH range 5.5 to 6.5. However, there were substantial differences in the ability of species to grow outside this range. Ginger and cassava were the most tolerant species to low solution pH, while ginger and tomato were the only species to show no yield depression at the highest solution pH. Roots of all species at pH 3.3 and some species at pH 4.0 exhibited symptoms of hydrogen ion injury. In addition, the concentrations of magnesium in the tops of all six species, of nitrogen in the tops of tomato and cassava, and of manganese in the tops of maize at these pH values were inadequate for optimal growth. Growth depression at high solution pH was associated with iron deficiency in maize and wheat and with nitrogen and/or copper deficiency in cassava. The relevance of the present results to crop growth under field conditions is discussed. The complex interplay of plant and soil characteristics militates against precise definition of an optimum pH range for the growth of a particular crop unless the soil is also specified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181830
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  • 10
    Electronic Resource
    Electronic Resource
    Tentacle contraction and ultrastructure inDiscophrya collini: The response to cations (1982)
    Springer
    Protoplasma 112 (1982), S. 92-100 
    Details
    ISSN: 1615-6102
    Keywords: Discophrya ; Tentacle contraction ; Cations ; Calcium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Discophrya collini is a suctorian protozoan with contractile tentacles containing a microtubule-lined canal and microfilaments. The effects of a range of cations on tentacle contraction and ultrastructure have been determined. Treatment with 80 mM CaCl2 and 95 mM MgCl2 causes contraction to 28% and 57% of the control length respectively. Re-extension takes over 4 hours in the culture medium, but CaCl2-treated tentacles are re-extended after a 5 minutes treatment with 10−2 M EDTA or 5 × 10−3 M EGTA. CuCl2 causes a significant contraction at 10−5 M (to 77%); LaCl3 at 10−4 M (to 65%); ZnCl2 at 10−2 M (to 65%), but BaCl2, CoCl2, MnCl2, NiCl2, and SrCl2 cause significant changes only at 10−1 M. The cytoplasm of CaCl2-treated cells contains two forms of membraneous structures when viewed in TEM; that of MgCl2-treated cells reveals granular areas of medium electron density. None of these features are seen in control cells. The microtubules of the tentacle canal appear to be intact upon its retraction into the cell with no change occurring in the numbers or relative positions of the microtubules. The tentacle cortex is wrinkled. It is suggested from this and previous work that tentacle contraction may be mediated by a microfilament-based mechanism, and that calcium may be involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280219
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