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  • Calcium  (20)
  • Scolytidae  (16)
  • Springer  (36)
  • 1980-1984  (36)
  • 1945-1949
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  • Springer  (36)
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  • 1
    Digitale Medien
    Digitale Medien
    Rhythmic dentinogenesis in the rabbit incisor: Allometric aspects (1980)
    Springer
    Calcified tissue international 32 (1980), S. 45-53 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Dentin ; Periodicity ; Allometry ; Calcium ; Sulfur
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02408520
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Rabbit ; Dentin ; Calcium ; Sulfur ; Periodicity ; Circadian ; Ultradian
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02408519
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Ecdysteroids during pupal development of female Xyleborus ferrugineus (1981)
    Springer
    Entomologia experimentalis et applicata 30 (1981), S. 151-156 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Xyleborus ferrugineus ; pupae ; ecdysteroids ; pharate adult ; radioimmunoassay ; Coleoptera ; Scolytidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Der Ecdysteroidtiter weiblicher Puppen von Xyleborus ferrugineus (Fabr.) wurde geschätzt, indem ganze Tiere homogenisiert und radioimmunologisch untersucht wurden. Ein ausgeprägtes Maximum an Ecdysteroiden wurde bei 36 Stunden Puppenent-wicklung beobachtet (743 pg/mg Körpergewicht). Der Titer nahm ab auf 299 pg/mg im Pharatstadium und auf 193 pg/mg unmittelbar vor Schlüpfen der Adulten. Qualitative Studien mit HPLC ergaben in frischen Puppen ein Verhältnis von 3:1 Ecdyson zu 20-Hydrooxyecdyson. Pharatstadien enthielten vor allem 20-Hydrooxyecdyson. Das beobachtete einzige Maximum im Titer stimmt überein mit den Resultaten bei andern untersuchten Coleopteren.
    Notizen: Abstract Ecdysteroid titers were estimated on the whole body homogenates of Xyleborus ferrugineus (Fabr.) female pupae during development by radioimmunoassay. A distinct peak of ecdysteroids was observed at 36-hr pupal development (743 pg/mg body wt). Titer declined to 299 pg/mg by the pharate adult stage and to 193 pg/mg body wt just before adult emergence. Qualitative studies by HPLC revealed a ratio of 3:1 ecdysone to 20-hydroxyecdysone in the initial pupal stage. Pharate adults had mainly 20-hydroxyecdysone. The observed single peak in ecdysteroid titer agrees with findings in other studied coleopteran species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00300880
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  • 4
    Digitale Medien
    Digitale Medien
    Pheromonal attraction and allomonal interruption ofIps pini in California by the two enantiomers of ipsdienol (1980)
    Springer
    Journal of chemical ecology 6 (1980), S. 703-717 
    Details
    ISSN: 1573-1561
    Schlagwort(e): Scolytidae ; bark beetle ; Ips pini ; pheromone ; ipsdienol ; enantiomer ; interruption ; allomone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Air containing volatile compounds from around maleIps pini boring in ponderosa pine logs from California was condensed, fractionated by GC, and assayed in the laboratory and field. The only fraction that showed consistent activity in laboratory assays contained a single compound identified as ipsdienol (2-methyl-6-methylene-2,7-octadien-4-ol). Synthetic racemic ipsdienol showed no activity in either the laboratory or field. However, (−)-ipsdienol, the naturally occurring enantiomer, was attractive toI. pini in the laboratory and field, whereas (+)-ipsdienol interrupted the response ofI. pini to a natural source of attraction in field tests. (−)-Ipsdienol is a major component of the attractant pheromone of this species, since its level of activity in laboratory assays was quantitatively comparable to that of the condensed volatiles, and it was as attractive as maleI. pini boring in ponderosa pine in the field. (+)-Ipsdienol is a component of the pheromone of the competing species,I. paraconfusus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00987680
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Pheromone production by axenically rearedDendroctonus ponderosae andIps paraconfusus (Coleoptera: Scolytidae) (1984)
    Springer
    Journal of chemical ecology 10 (1984), S. 281-290 
    Details
    ISSN: 1573-1561
    Schlagwort(e): Dendroctonus ponderosae ; Ips paraconfusus ; Coleoptera ; Scolytidae ; axenic rearing ; monoterpenes ; aggregation pheromones ; trans-verbenol ; exo-brevicomin ; ipsenol ; ipsdienol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Mountain pine beetles,Dendroctonus ponderosae Hopkins, and California five-spined ips,Ips paraconfusus Lanier, were reared axenically from surface-sterilized eggs on aseptic pine phloem. After 24 hr in host logs, axenip femaleD. ponderosae and maleI. paraconfusus produced the aggregation pheromones,trans-verbenol (D. ponderosae), and ipsenol and ipsdienol (I. paraconfusus). Emergent, axenically reared maleD. ponderosae contained normal amounts of the pheromoneexo-brevicomin. Axenic femaleD. ponderosae treated with juvenile hormone or exposed to vapors of α-pinene, produced the pheromonetrans-verbenol. By 25–35 days after eclosion, axenic females exposed to α-pinene vapors produced over six times as muchtrans-verbenol as wild females, suggesting that while microorganisms in wild females may producetrans-verbenol, they may also inhibit production of the pheromone or use it as a substrate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00987856
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Tentacle contraction inDiscophrya collini: The effects of ionophore A23187 and ruthenium red on Ca2+-induced contraction and uptake of extracellular calcium (1984)
    Springer
    Protoplasma 122 (1984), S. 125-131 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Calcium ; Contraction ; Discophrya ; Ionophore A23187 ; Ruthenium red ; Tentacles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The tentacles of the suctorian protozoonDiscophrya collini are stimulated to contract by externally applied Ca2+. The role of extracellular Ca2+ in tentacle contraction was studied by monitoring45Ca2+ uptake, using ionophore A23187 to facilitate membrane transport of calcium and ruthenium red (RR) as an inhibitor of transport. The degree of tentacle retraction was dependent upon external Ca2+ concentration and studies with45Ca2+ using scintillation counting indicated a linear relationship between external Ca2+ concentration and Ca2+ uptake. Uptake of Ca2+ was enhanced in the presence of the ionophore while RR caused little inhibition.45Ca2+ uptake was only partially inhibited by RR when cells were subjected to a Ca2+, ionophore and RR mixture. Grain counts from light microscope autoradiographs after treatment of cells with45Ca2+/ionophore,45Ca2+/RR or45Ca2+ alone showed heavy, light and intermediate labelling respectively. In all instances the grains were evenly distributed within the cell. These observations are interpreted as supporting the suggestion that the ionophore enhances both the uptake of extracellular Ca2+ and release of Ca2+from an internal source, while the RR could only partially prevent movement of Ca2+ through the plasma mebrane. A model is presented suggesting that tentacle retraction is mediated by cytosolic Ca2+ levels which are determined by the fluxing of Ca2+ across the plasma membrane and the membrane of elongate dense bodies which act as internal Ca2+ reservoirs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01279445
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  • 7
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Hydroxyapatite ; Dissolution ; Pyrophosphate, Diphosphonates ; Calcium ; Phosphate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02407176
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  • 8
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): 1α-Hydroxy vitamin D3 ; 1,25-Dihydroxyvitamin D3 ; Calcium ; Transport ; Intestine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02408517
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  • 9
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Ultrastructure ; Calcium ; Cartilage ; Vesicles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02408603
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  • 10
    Digitale Medien
    Digitale Medien
    Calcium distribution in freeze-dried enamel organ tissue during normal and altered enamel mineralization (1984)
    Springer
    Calcified tissue international 36 (1984), S. 596-603 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Calcium ; Ameloblasts ; X-ray microanalysis ; Transport ; Frozen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Energy dispersive X-ray microanalysis was applied to freeze-dried blocks of enamel organ tissue to determine levels of calcium in various celular regions. The tissue blocks were dissected free from adjacent forming enamel following injection of cobalt or fluoride ions, both of which temporarily inhibit enamel mineralization. In all control and experimental specimens there was an increasing gradient of calcium from the stratum intermedium cells to the distal ends of the ameloblasts. Calcium levels were significantly reduced near the distal ends of the ameloblasts following cobalt or fluoride injection as compared with controls. It is suggested that evidence of an intercellular buildup of calcium near the distal ends of the ameloblast supports a controlling function of these cells. The changes in calcium levels are correlated with alterations in mineralization known to occur in the adjacent enamel of the model systems employed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02405373
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