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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This paper describes a simple chromatographic technique on Sephadex LH20 for the separation of vitamin D3 sulfate from free vitamin D3 and its metabolites. This technique has been used in the study of vitamin D3 sulfate metabolism in rats. Seven hours after injection of vitamin D3 sulfate (35S or 35S and 3H) only the peak of vitamin D sulfoconjugate was found in chromatographic elution of serum extracts.
Steroids 1978 May
PMID:Chromatographic separation of vitamin D3 sulfate and vitamin D3. 20 79

Since intestinal calcium-binding protein (CaBP) can be regarded as an expression of the hormone-like action of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on the duodenal enterocyte we have investigated the potential biological activity of 25R and 25S,26-(OH)2D3 (two recently synthesized epimers of vitamin D3 metabolite) to promote intestinal CaBP production as compared to bone calcium mobilization in vitamin D and calcium-deficient rats. In our assay steroids exhibited a 72 hour calcemic response. Our results show a linear relationship between CaBP synthesis and the logarithm of the dose (130-2080 pmol dose range) of either 25R or 25S epimer. The CaBP response was comparable for both epimers. Similarly bone calcium mobilization response was dose related as a linear function of the logarithm of the administered dose. Again, calcemic response was comparable for both epimers. In our model these two epimers were about as active on intestine to increase CaBP amount as on bone to elevate serum calcium level. Bilateral nephrectomy abolished CaBP response to a large dose (1040 pmol) of either 25R or 25S epimer but did not abolish it to a 130 pmol dose of 1alpha,25-(OH)2D3.
Steroids 1978 Dec
PMID:Intestinal calcium-binding protein (CaBP) and bone calcium mobilization in response to 25R,26 and 25S,26-dihydroxycholecalciferol in intact and nephrectomized rats. 73 93

The binding of metabolites of vitamin D and their analogs to the 3.7S chick intestinal cytosol receptor protein has been specifically studied by competitive binding techniques and polyethylene glycol precipitation of the complex. The structural requirements for the interaction between the vitamin D molecule and the receptor could be assessed without the nuclear chromatin binding step. These measurements have shown that 1,25-dihydroxyvitamin D3 and 1,25-dihydroxyvitamin D2 are equally competitive and are the most active. Of the structural features of the compounds, the 1 alpha-hydroxyl is most important followed by the 25-hydroxyl and the 3 beta-hydroxyl. The addition of a second hydroxyl near carbon 25 markedly reduces binding whether on the 26 carbon or the 24 carbon. A hydroxyl on C-24 could substitute to some degree for the 25-hydroxyl inasmuch as 24-hydroxyvitamin D3 was much more effective than vitamin D3 but less effective than 25-hydroxyvitamin D3. In general the patterns of binding affinities correlated well with the biological activity of the various analogs strongly supporting a physiological role for the 1,25-dihydroxyvitamin D3 binding protein. It also suggests that of the two-step receptor mechanism, the structural specificity is located in the initial interaction of the 1,25-dihydroxyvitamin D3 and the cytosol receptor.
Steroids 1977 Aug
PMID:Intestinal 1,25-dihydroxyvitamin D3 binding protein: specificity of binding. 92 48

The concentrations of the 25-hydroxy and 24R, 25-dihydroxy derivatives of vitamin D were determined in 100 microliter l plasma samples using calciferol binding globulin from bovine plasma. Sufficient quantities of 24R, 25-dihydroxy vitamin D were found in bovine, porcine, chicken and human plasma to interfere in the assay of 25-hydroxy vitamin D in unfractionated extracts. No metabolites of vitamin D could be found in rainbow trout plasma.
Steroids 1977 Aug
PMID:A binding assay for 25-hydroxycalciferols and 24R,25-dihydroxycalciferols using bovine plasma globulin. 92 49

25xi,26-Dihydroxycholecalciferol (25xi,26-dihydroxyvitamin D3), a metabolite of vitamin D3 preferentially active on intestine has been synthesized. This compound was prepared by converting 3beta-hydroxy-27-norcholest-5-en-25-one to 25xi,26-epoxy-5-cholesten--3beta-ol and base-catalyzed hydrolysis of the latter to 5-cholestene-3beta,25xi,26-triol; allylic bromination of the corresponding triacetate, and dehydrobromination gave the required 5,7-diene which yielded the vitamin derivative upon photolysis (Figure 3). The synthetic product shows the same activity pattern as the natural metabolite: at dose levels of 0.25 mug, the compound stimulates intestinal calcium transport, but has no effect on bone calcium mobilization in rats maintained on a vitamin D-deficient, low calcium diet. Higher doses (2.5 mug) elicit a more pronounced intestinal calcium transport response, but also have no significant effect on the bone mobilization system. The compound exhibits no biologial activity in nephrectomized animals.
Steroids 1975 Feb
PMID:Synthesis and biological activity of 25xi,26-dihydroxycholecalciferol. 111 66

8(14)a-Homocalcitriol was synthesized and tested for its biologic activities. It exhibited a vitamin D agonist activity profile. The compound was bound to the pig intestinal receptor with an affinity slightly less than calcitriol, showed the same potency in inducing HL 60 cell differentiation and inhibition of keratinocyte proliferation as calcitriol, and was found to be approximately 10-fold less potent in inducing hypercalcemia and hypercalciuria after a single injection in normal rats.
Steroids 1992 Sep
PMID:Synthesis and biological activities of 8(14)a-homocalcitriol. 133 55

Dihydrotachysterol3, a reduced (or hydrogenated) analog of vitamin D3 in which the A ring has been rotate through 180 degrees , is, after hepatic 25-hydroxylation, converted in vivo to a dihydroxylated metabolite, termed peak H, which is at present unidentified but with good affinity for the vitamin D receptor. Although peak H is made in relatively large amounts in vivo, it has not yet been possible to synthesize it in vitro. Mass spectrometric evidence suggests that peak H is 25-hydroxylated and the presumption that it is a metabolite of 25-hydroxydihydrotachysterol3 was confirmed by the demonstration that radiolabeled peak H was formed in vivo in the rat after injection of 25-hydroxy-[10,19-3H]dihydrotachysterol3, produced from [10,19-3H]dihydrotachysterol3 in a hepatic cell model. The metabolism of 25-hydroxy-[10,19-3H]dihydrotachysterol3 was also studied in a rat osteosarcoma cell UMR-106, a known target cell for vitamin D, using high (11 microM) and low (10 nM) substrate concentrations. Metabolic products were isolated by lipid extraction, purified by high-performance liquid chromatography, and characterized by direct-probe mass spectrometry and gas chromatography/mass spectrometry. The formation of peak H from 25-hydroxydihydrotachysterol3 could not be demonstrated in UMR-106 cells. However, 25-hydroxydihydrotachysterol3 was metabolized to at least seven side-chain modified metabolites, each of which was extensively characterized and tentatively identified. It is concluded that the vitamin D enzyme system present in UMR-106 cells is able to metabolize dihydrotachysterol3 very efficiently to a series of metabolites but is incapable of producing peak H.
Steroids 1992 May
PMID:Metabolism of 25-hydroxydihydrotachysterol3 in bone cells in vitro. 133 6

Following the revelation of the presence of vitamin D in fish liver oils and of estrogenic hormones in pregnancy urine in the 1920s, active interest in the steroids began in England. Most of this interest originated from the studies of Ian Heilbron at Liverpool and of Otto Rosenheim at the National Institute for Medical Research in London.
Steroids 1992 Aug
PMID:Early English steroid history. 151 66

Monocytic differentiation-inducing activity of steroidal side chain-lengthened 26,27-dialkyl analogs of 1 alpha,25-dihydroxyvitamin D3 was examined in human promyelocytic leukemia (HL-60) cells in serum-supplemented or serum-free culture. The order of in vitro potency for reducing nitroblue tetrazolium was 1 alpha,25-dihydroxy-26,27-dimethylvitamin D3 greater than or equal to 1 alpha,25-dihydroxy-26,27-diethylvitamin D3 much greater than 1 alpha,25-dihydroxy-26,27-dipropylvitamin D3 under serum-free culture conditions. Analysis by sucrose density-gradient centrifugation or polyethylene glycol precipitation technique showed that the potency order for differentiation-inducing activity correlated well with binding affinity of these analogs for vitamin D3 receptor of HL-60 cells. Under serum-supplemented culture conditions, the lack of correlation between biologic activity and analog-binding affinity for receptor was caused by differences in binding affinity of these analogs for serum vitamin D-binding proteins. These results suggest that serum vitamin D-binding proteins apparently modulate monocytic differentiation of HL-60 cells by these analogs under serum-supplemented culture conditions.
Steroids 1991 Mar
PMID:Effects of novel 26,27-dialkyl analogs of 1 alpha,25-dihydroxyvitamin D3 on differentiation-inducing activity of human promyelocytic leukemia (HL-60) cells in serum-supplemented or serum-free culture. 164 92

A novel synthesis of side-chain homologated analogs of vitamin D isomers has been described. The synthesis allows for the insertion of the double bond into the C-24 position of the side chain. The key synthetic step involves the coupling of a new C24-vitamin D synthon with the respective side-chain fragment. The method is illustrated by the preparation of (24E)-24,24a-dehydro-24,24-dihomo-1,25-dihydroxycholecalcife rol (1) and (24b R)- and (24b S)-24,24-dihomo-1,25-dihydroxyergocalciferols (2 and 3). Trans geometry of the newly formed double bond in the side chain was confirmed by high field nuclear magnetic resonance spectra.
Steroids 1991 Jun
PMID:Synthesis of side-chain homologated analogs of 1,25-dihydroxycholecalciferol and 1,25-dihydroxyergocalciferol. 192 26


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