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  • 1
    Electronic Resource
    Electronic Resource
    Calcium regulating activity of 26,27-dimethyl analog of 24R,25-dihydroxyvitamin D3 (1994)
    Springer
    Calcified tissue international 55 (1994), S. 190-197 
    Details
    ISSN: 1432-0827
    Keywords: Bone resorption ; Osteoclast-like cell formation ; Bone Ca mobilization ; Intestinal Ca transport ; 24R,25-dihydroxy-26,27-dimethylvitamin D3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract To determine the possibility that methyl substitution in 26- and 27-positions of 24R,25-dihydroxyvitamin D3 [24,25(OH)2D3] alters activities of the original compound, the effects of 24,25(OH)2D3 on calcium (Ca) regulating activity were compared with those of its methyl analog [24,25(OH)2(CH3)2D3] in addition to 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3]. 24,25(OH)2D3 at 10-6 M and 24,25(OH)2(CH3)2D3 at 10-7 M and above significantly stimulated both bone resorption in neonatal mouse calvaria cultures and formation of osteoclast-like multinucleated cells (MNC) in mouse bone marrow cultures. A stimulative effect of 1,25(OH)2D3 on bone resorption and MNC formation was recognized in very low concentrations (10-11 M and above). Although a potency of 24,25(OH)2(CH3)2D3 in stimulating bone calcium (Ca) mobilization and intestinal Ca transport was higher than that of 24,25(OH)2D3, the potencies of both compounds were similar to that of 1,25(OH)2D3 unlike in vitro experiments. As 1,24R,25-trihydroxy-26,27-dimethylvitamin D3 showed almost the same effect as 24,25(OH)2(CH3)2D3, the dihydroxy form is suggested to be hydroxylated at 1α position and converted to trihydroxy form in vitamin D-deficient rats. From these results, methyl substitution in 26- and 27-position of 24,25(OH)2D3 was found to elevate Ca regulating activity of the original compound. In addition, it is suggested that the basis for a similarity in potency between 1,25(OH)2D3 and 24,25(OH)2D3 or its dimethyl analog in vitamin D-deficient rats is likely the result of 1 α-hydroxylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425874
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Characteristics of binding of [3H]NE-100, a novel sigma-receptor ligand, to guinea-pig brain membranes (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 244-251 
    Details
    ISSN: 1432-1912
    Keywords: Key words Sigma binding sites ; NE-100 ; (N ; N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy) phenyl]-ethylamine monohydrochloride) ; Radiolabeled ligand binding ; Brain ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We examined the characteristics of binding of radiolabeled N,N-dipropyl-2-[4-methoxy-3-(2-phenyl- ethoxy)phenyl]-ethylamine monohydrochloride ([3H] NE-100), a highly potent and selective sigma-receptor ligand, to guinea-pig brain membranes. [3H]NE-100 showed saturable and reversible binding to sigma binding sites. A dissociation constant (Kd) and maximal numbers of binding sites (B max) obtained from Scatchard plot analysis were 1.2±0.1 nM and 1049.3±115.1 fmol/mg protein (n=3), respectively. NE-100 was the most potent inhibitor of [3H]NE-100 binding among several structurally dissimilar sigma-receptor ligands, including haloperidol and (+)-pentazocine. (+)-Benzomorphanes had more than a 10-fold potent inhibitory activity over (−)-benzomorphanes, with regard to [3H]NE-100 binding. The binding of [3H]NE-100 was not influenced by histaminergic, dopaminergic, adrenergic, serotonergic cholinergic or glutaminergic agents at 10-7 M. GTP-γ-S and phenytoin also did not affect the binding of [3H]NE-100. A higher [3H]NE-100 binding was observed in the cerbellum and medulla oblongata. Except for the nuclear fraction, the highest level of [3H]NE-100 binding to subcellular fractions was observed in microsomal fractions. These results suggest that NE-100 selectively binds, with a high affinity, to sigma-1 binding sites in guinea-pig brain membranes, as an “antagonist”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233243
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    Paper (German National Licenses)
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