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  • Electronic Resource  (2)
  • 1995-1999  (1)
  • 1990-1994  (1)
  • 1980-1984
  • 1960-1964
  • 24-epi-1α-hydroxyvitamin D2  (1)
  • Acclimation  (1)
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  • Electronic Resource  (2)
Years
  • 1995-1999  (1)
  • 1990-1994  (1)
  • 1980-1984
  • 1960-1964
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Bone-resorbing activities of 24-epi-1α-hydroxyvitamin D2 and 24-epi-1α,25-dihydroxyvitamin D2 (1995)
    Springer
    Calcified tissue international 56 (1995), S. 49-53 
    Details
    ISSN: 1432-0827
    Keywords: Bone resorption ; Osteoclast formation ; Resorption lacunae ; 24-epi-1α-hydroxyvitamin D2 ; 24-epi-1α,25-dihydroxyvitamin D2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Bone-resorbing activities of 24-epi-1α-hydroxyvitamin D2 [24-epi-1α(OH)D2], 24-epi-1α,25-dihydroxyvitamin D2 [24-epi-1,25(OH)2D2], and 1α,24S,25-trihydroxyvitamin D2 [1,24S,25(OH)3D2], which might be a metabolite of 24-epi-1,25(OH)2D2, were investigated. In an in vitro bone resorption test, the activity of 24-epi-1α(OH)D2 was similar to that of 1α-hydroxyvitamin D3 [1α(OH)D3] at 10-9 M-10-6 M. The activity of 24-epi-1,25(OH)2D2 was weaker than that of 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] at 10-11 M-10-8 M. On the other hand, the activity of 1,24S,25(OH)3D2 was similar to that of 24-epi-1,25(OH)2D2 at 10-11 M-10-9 M. In the formation assay of osteoclast-like cells, the activity of 24-epi-1α(OH)D2 was weaker than that of 1α(OH)D3 at 10-7 M. The activity of 24-epi-1,25(OH)2D2 was almost similar to that of 1,25(OH)2D3 at 10-11 M-10-7 M. The activity of 1,24S,25(OH)3D2 was significantly weaker than that of 24-epi-1,25(OH)2D2 at 10-11 M-10-9 M. In the two experiments, the potencies of 24-epi-1,25(OH)2D2 were about 100 times higher than those of 24-epi-1α(OH)D2. In an in vivo/in vitro bone resorption test, the activity of 24-epi-1α(OH)D2 was almost similar to those of 1α(OH)D3 and 1,25(OH)2D3 and higher than those of 24-epi-1,25(OH)2D2 and 1,24S,25(OH)3D2. 24-epi-1α-(OH)D2 and 1α(OH)D3 were longer lasting than 24-epi-1,25(OH)2D2 and 1,25(OH)2D3 in this experiment. These results suggested that 24-epi-1α(OH)D2 as well as 1α(OH)D3 was converted into dihydroxy form in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298744
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Changes in carp myosin ATPase induced by temperature acclimation (1990)
    Springer
    Journal of comparative physiology 160 (1990), S. 233-239 
    Details
    ISSN: 1432-136X
    Keywords: Temperature ; Acclimation ; Myosin ; Myosin heavy chain ; ATPase activity ; Carp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Myosins were isolated from dorsal ordinary muscles of carp acclimated to 10°C and 30°C for a minimum of 5 weeks and examined for their ATPase activities. Ca2+-ATPase activity was different between myosins from cold-and warm-acclimated carp, especially at KCl concentrations ranging from 0.1 to 0.2 M, when measured at pH 7.0. The highest activity was 0.32 μmol Pi·min-1·mg-1 at 0.2 M KCl for cold-acclimated carp and 0.47 μmol Pi·min-1·mg-1 at 0.1 M KCl for warm-acclimated fish. The pH-dependency of Ca2+-ATPase activity at 0.5 M KCl for both carp was, however, similar exhibiting two maxima around 0.3 μmol Pi·min-1·mg-1 at pH 6 and 0.4 μmol Pi·min-1·mg-1 at pH 9. K+(EDTA)-ATPase activity at pH 7.0 neither exhibited differences between both myosins. It increased with increasing KCl concentration showing the highest value of about 0.4 μmol Pi·min-1·mg-1 at 0.6–0.7 M KCl. Actin-activated myosin Mg2+-ATPase activity was markedly different between cold-and warm-acclimated carp. The maximum initial velocity was 0.53 μmol Pi·min-1·mg-1 myosin at pH 7.0 and 0.05 M KCl for cold-acclimated carp, which was 1.6 times as high as that for warm-acclimated carp. These differences were in good agreement with those obtained with myofibrillar Mg2+-ATPase activity between both carp. No differences were, however, observed in myosin affinity to actin. Differences in myosin properties between cold- and warm-acclimated carp were further evidenced by its thermal stability. The inactivation rate constant of myosin Ca2+-ATPase was 25·10-4·s-1 at 30°C and pH 7.0 for cold-acclimated carp, which was about 4 times as high as that for warm-acclimated carp. Light chain composition did not differ between both carp myosins. The differences in a primary structure of the heavy chain subunit was, however, clearly demonstrated between both myosins by peptide mapping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302588
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    Paper (German National Licenses)
    Fulltext
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